Percentages & Profit Loss - 1 | CAT Preparation 2024 | Arithmetic | Quantitative Aptitude

Summary

In this educational video, Ravi Prakash introduces the fundamental concepts of percentages, emphasizing their importance in arithmetic, calculations, and data interpretation. He covers the conversion of fractions to percentages, provides a series of fraction-to-percentage values, and explains how to apply these in various quantitative problems. Prakash also discusses the concept of 'multiplying factors' for quick calculations involving percentage increases or decreases, demonstrating how to simplify complex percentage problems into straightforward multiplications.

Takeaways

• 📚 The script is a lecture on percentages, emphasizing their importance in various mathematical and real-world applications.
• 🔢 It covers the conversion of fractions to percentages, using multiplication by 100 to find the percentage value of a fraction.
• 📈 The instructor provides a method to quickly calculate percentages by relating them to fractions and remembering key values like 1/2 equals 50%, 1/3 equals 33.33%, etc.
• 📝 The script mentions 'speed math' techniques for quick calculations, suggesting that viewers should watch related videos for a refresher.
• 🧠 Memorization is stressed for certain fractions and their corresponding percentages, such as 1/8 being 12.5% and 3/8 being 37.5%.
• 🔑 The concept of 'multiplying factors' is introduced, which is crucial for understanding how to increase or decrease a number by a certain percentage.
• 🛠️ The 'multiplying factor' is explained as either 1 plus the fraction value for an increase or 1 minus the fraction value for a decrease.
• 📉 For decrease problems, the script shows how to use the fraction of the decrease as a multiplying factor by subtracting it from 1.
• 📈 Conversely, for increase problems, the fraction value is added to 1 to find the multiplying factor.
• 📝 The importance of understanding and memorizing these multiplying factors is highlighted for solving a variety of quantitative problems quickly.
• 🎓 The lecture concludes by reinforcing the importance of mastering percentages for success in quantitative aptitude sections of competitive exams.

Q & A

What is the main topic of the video?

The main topic of the video is percentages, covering their importance, basic concepts, and calculations.

Why are percentages considered an important topic in arithmetic?

Percentages are important in arithmetic because they form the foundation for solving various problems, calculations, and data interpretation sets.

What is the relationship between fractions and percentages?

Fractions can be converted to percentages by multiplying the fraction by 100. For example, 1/2 is equal to 50%.

What is the percentage equivalent of the fraction 1/3?

The fraction 1/3 is equivalent to 33.33%.

How can you remember the percentage of 1/7?

You can remember the percentage of 1/7 as approximately 14.28%, using the mnemonic '7 two fourteen fourteen two eight'.

What is the purpose of the 'multiplying factor' concept in percentages?

The 'multiplying factor' concept helps in quickly calculating the result of increasing or decreasing a number by a certain percentage.

How do you calculate the multiplying factor for a decrease of 20%?

To calculate the multiplying factor for a 20% decrease, you use the formula 1 minus the fraction value, which in this case is 1 - 1/5, resulting in 4/5.

What is the percentage of 1/19 when multiplied by 100?

When 1/19 is multiplied by 100, it becomes approximately 5.26%.

How can you find the value of 37.5% of a number using the script's method?

You can find the value of 37.5% of a number by recognizing that 37.5% is equivalent to 3/8 of the number and then multiplying the number by 3/8.

What is the significance of remembering specific percentage values in the script?

Remembering specific percentage values helps in quickly solving various quantitative problems and is useful in different areas of arithmetic, including profit and loss, time and distance, and data interpretation.

How can you find the result of decreasing a number by 87.5% using the multiplying factor?

To find the result of decreasing a number by 87.5%, you multiply the number by the multiplying factor, which is 1 minus the fraction value of the percentage, in this case, 1 - 7/8 or 1/8.

Outlines

00:00

📚 Introduction to Percentages

The script introduces Ravi Prakash, the instructor, and the topic of percentages, emphasizing its importance in arithmetic, calculations, and data interpretation. The instructor suggests watching 'speed math' videos for a strong foundation in percentages. Basic fraction to percentage conversions are taught, illustrating the process of multiplying fractions by 100 to find their percentage equivalents, with examples ranging from 1/2 to 1/19, highlighting the significance of memorizing these conversions for quick calculations.

05:00

🔢 Fractions and Percentages Conversion

This paragraph delves deeper into the conversion of fractions to percentages, providing specific examples and mnemonic techniques for remembering them. It covers fractions like 1/7, 1/8, and 1/9, and introduces the concept of approximation for more complex fractions. The importance of understanding these conversions for quick calculations in quantitative aptitude sections of exams is stressed, along with the idea of deriving new values from known ones.

10:01

🧮 Applying Percentages to Calculations

The script explains how to use the percentage values derived from fractions to perform calculations, such as finding what percentage of a number is represented by another number. It provides a series of examples, including calculating 37.5% of 640 and 18.75% of 176, demonstrating the process of breaking down percentages into their fraction equivalents and simplifying the calculations using known values.

15:03

📈 Understanding Multiplying Factors in Percentages

The concept of multiplying factors in the context of percentage increase and decrease is introduced. The instructor explains how to find the new value of a number after a certain percentage change by using multiplying factors, which are derived from the percentage's fraction equivalent. Examples are given to illustrate how to quickly calculate the result of percentage changes using these factors.

20:04

🤝 The Role of Multiplying Factors in Problem Solving

This section emphasizes the utility of multiplying factors in a variety of quantitative problems, including profit and loss, simple interest, mixtures, time and distance, and data interpretation. The instructor provides a method to determine multiplying factors for both increases and decreases, using the formula of 1 plus or 1 minus the fraction value of the percentage change, and illustrates this with examples involving different percentage decreases.

25:04

🎓 Conclusion and Continuing Education

The final paragraph wraps up the video by summarizing the importance of understanding multiplying factors for quick and accurate calculations in various quantitative problems. The instructor encourages the viewers to continue learning and practicing with a variety of questions to solidify their understanding of percentages and their applications.

Keywords

💡Percentage

A percentage is a way of expressing a number as a fraction of 100. It is fundamental to the video's theme as it is the main topic being discussed and taught. The script explains how to convert fractions to percentages, such as 'one by one' being 'hundred percent', and uses this concept to solve various arithmetic problems related to percentages.

💡Fraction to Percentage Conversion

This concept is central to the video, where the instructor demonstrates how to convert fractions into percentages by multiplying the fraction by 100. For instance, 'one by two' is converted to 'fifty percent', illustrating the basic arithmetic involved in understanding percentages.

💡Arithmetic Problems

Arithmetic problems are mathematical problems involving the basic operations of addition, subtraction, multiplication, and division. In the script, the instructor emphasizes that understanding percentages is essential for solving all types of arithmetic problems, including those involving calculations and data interpretation.

💡Data Interpretation

Data interpretation is the process of understanding and analyzing data. The video mentions that percentages are crucial for data interpretation sets, indicating that the ability to work with percentages aids in making sense of numerical data and drawing conclusions from it.

💡Speed Math

Speed Math refers to the techniques used to perform calculations quickly and efficiently. The script suggests that viewers should watch speed math videos to boost their confidence in handling percentages quickly, implying that there are specific strategies to enhance calculation speed.

💡Multiplying Factor

The multiplying factor is a concept introduced in the script that refers to the factor by which a number is increased or decreased. For example, if a number is decreased by a certain percentage, the multiplying factor would be used to find the new value. The script explains that understanding multiplying factors can simplify the process of percentage calculations.

💡Approximation

Approximation is the process of rounding a number to a near value for ease of calculation or understanding. The instructor uses approximation in the script to simplify the conversion of certain fractions to percentages, such as 'one by seventeen' being approximated to 'five point eight eight percent'.

💡Quantitative Aptitude

Quantitative Aptitude refers to the ability to understand and solve numerical and mathematical problems. The script mentions that the concepts taught in the video, such as percentages, are used throughout quantitative aptitude sections in various competitive exams, emphasizing the importance of mastering these concepts.

💡Profit and Loss

Profit and Loss is a financial term used to describe the difference between the cost of goods sold and the revenue generated from their sale. The script indicates that percentages are very important in calculating profit and loss, as they help determine the gain or loss as a proportion of the cost price.

💡Time and Distance

Time and Distance is a category of problems that involve calculating speed, time taken, or distance covered based on given conditions. The video script mentions that percentages are used in time and distance problems, such as calculating the speed of an object when a certain percentage of time has passed.

💡Mixtures

Mixtures, in the context of this video, likely refer to problems involving the combination of different substances or quantities, often requiring the use of percentages to determine the proportion of each component in the final mixture. The script suggests that understanding percentages is essential for solving such problems.

Highlights

Introduction to the importance of percentages in foundational arithmetic and data interpretation.

The significance of watching speed math videos to boost confidence in percentage calculations.

Fraction to percentage conversion method explained using multiplication by 100.

Memory aids for common fractions like 1/2, 1/3, and 1/4 and their percentage equivalents.

The concept of 'per 100' in percentages and its relation to the word 'century'.

Quick calculation technique for fractions like 1/7 and 1/8 by relating them to known percentages.

The strategy of connecting fractions to simplify percentage calculations, such as relating 1/12 to 1/6.

Understanding the unique value of fractions like 1/17 and 1/19 in percentage calculations.

The method of deriving percentage values from known fractions for complex calculations.

The importance of memorizing specific fraction-to-percentage conversions for quick problem-solving.

The concept of multiplying factors in percentages for quick calculation of increases or decreases.

How to find the percentage of a number using fraction multiplication, exemplified with 37.5% of 640.

Breaking down complex percentages into simpler fractions for easier calculation, like 18.75%.

The use of fraction series to simplify percentage calculations, such as the 12.5% series.

Techniques for approximating percentage calculations for tough fractions like 1/23.

The application of multiplying factors to quickly find results for percentage increase or decrease problems.

The final summary emphasizing the importance of understanding percentages for various quantitative aptitude tests.

Transcripts

[Music]

[Music]

hi everyone my name is ravi prakash and

welcome to first class of percentages

percentage is super important topic

every line i say every question i solve

so important in this percentage topic

right because this will build up your

foundation to solve all the arithmetic

problems all the calculations all the

data interpretation sets right

everywhere this percentage will help

okay i have to be very good at

percentages solving percentages

i hope you have watched speed man we

have watched those speed match videos

where we discussed how to do fast

calculation in percentages right so all

those things very important percentages

okay

so before percentages please watch those

uh speed match videos right further

boost up your

confidence in percentages okay so let's

start percentages one

first class of percentages right now see

here

first we will see

all the

fraction

fraction

to percentage conversion we should

remember it right fraction to percent is

conversion

like start starting from

one by one

obviously one by one is what one by one

is hundred percent

right one by two what is one by two

fifty percent

we should remember to 1 by 19 okay what

is 1 by 3

33.33 percent right what i'm doing

actually is any fraction

any fraction multiplied by 100 will give

me the percentage value

right so half into hundred is what fifty

so fifty percent okay one by three into

hundred so it is hundred by three what

is hundred by three thirty three point

three three

so when you multiply any fraction by

percent a hundred it becomes percentage

right because what is percentage means

percentages means per 100 percentages

means per 100 okay percent per cent

percent sentiments sent means 100 okay

so percent the sentence in century word

also century century contains cent right

so sent means hundred century means

hundred okay

so

again so do all this right now one by

four you can calculate you can remember

easily also right what is one by four

one by four into hundred is what one by

four into hundred twenty five percent

okay one by five and two hundred is what

twenty percent okay now one by six now

you can connect this now you can connect

it now what is one by six here you see

one by three half is one by six so what

is thirty three point three three half

sixteen point six six percent

correct now what is one by seven

so what is one by seven

so again now seven you can't connect

with the previous one because one by

seven it is right one by seven when you

multiply it by hundred it becomes

hundred by seven so i know seven

fourteen ja ninety eight and 2 is left

so 14 plus 2 by 7

is written by 14 2 by 7 but in decimal

right so 1 by 7 is approximately 0.14

1 by 7 is approximately 0.14 so 2 by 7

is approximately 0.28 you can remember

it

14.28 percentage

okay one by seven fourteen point two

eight percent easy to remember also

because seven two fourteen fourteen two

twenty eight

so it's easy to remember then one by

eight one by eight is what it is half of

one by four what is one by four twelve

four twenty five percent what is half of

twenty five twelve point five percent

one by nine again nine is not a prime

number you can easily connect with any

previous one 1 by 9 is what 1 by 9 is

one third of one one by three one by

nine is one third of one by three what

is one by three thirty three point three

three it's one third how much eleven

point one one percent

okay one by ten is obviously ten percent

which i should not write this okay one

by ten is ten percent one by ten

multiplied by hundred ten percent one by

eleven

again you solve like this one by eleven

into hundred so see 1 by 11 into 100 let

me write here

each step is so important right how to

calculate being making calculation here

your calculation making fast okay

1 by 11 in 200

ninety nine

so nine plus one by eleven is left this

is nine one by eleven in which fraction

and which fraction is plus sign is

hidden okay nine one by eleven so nine

one by eleven is what what is one by

eleven

one by eleven is approximately point

zero nine so it is how much it is nine

point

zero nine percent is okay now one by

twelve

so how much one by twelve one by nine

twelve is not a prime number and we can

connect with another any previous one

value so one by twelve is half of one by

six what is one by six

sixteen point six six percent okay half

of sixteen point six six percent eight

point three three percent what is one by

thirteen

one by thirty is what seven point seven

percent okay seven point seven percent

remember it one by thirteen is seven

point seven percent

seven point six nine to be exact but you

can remember seven point seven so

one by fourteen

what is 1 by 14 half of 1 by 7 14.28

half is how much 7.14 percent you

remember this value right remember is so

important till 1 by 19.

now 1 by 15.

now what is 1 by 15 it is one third of 1

by 5. it is one third of one by five

what is one by five twenty percent one

third of twenty percent how much

six point six six percent okay twenty by

three is six point six six one by

sixteen what is one by sixteen

it is half of one by eight what is one

by eight twelve point five twelve point

five half is how much six point two five

percent okay one by seventeen what is

one by seventeen so again remember here

one by seventeen is five point eight

eight

right you can sense this value actually

so one by this kind of value values

right when it gets tougher now or one by

17 and all so 1 by 17 into 100 if you

multiply so 1 by 17 into 100 how much it

is

so 17 6 java 1 0 2 so it is just

slightly less than 6 slightly less than

6 right because 17 into 6 is 1 0

slightly less than 6 5.8 percent this

kind of approximation you can do okay

now

1 by 18

1 by 18

it is 1 by 18 it is half of 9.09 sorry

it is half of 1 by 9 what is half of 1

by what is one by nine eleven point one

one what is half of eleven point one one

so eleven point one half is what five

point five five

what is one by nineteen

so one minute is what it is

five we remember five point two six

percent

see i'll discuss one by nineteen also

this

approximations you should understand

one by nineteen

when multiplied by hundred

it becomes nineteen five ninety five

5 is left because it is 100 here 5 plus

5 by 19.

now what is value of 5 by 19 so had it

been 5 by 20 so 5 by 20 was exactly 1 by

4 what is 1 by 4.25 right had it been

had it been

had it been five by twenty so five by

twenty is exactly one by four that is

point two five but it is five by

nineteen so five by deliver then five by

twenty is slightly more because

derivative is less so fraction is

slightly more so 0.25 slightly more

right so we're right here 0.26 that's

why

okay so what is one by 19 around 5.26

percent right this kind of

approximations you can make very

important this data very important okay

because this is only the unique table

right now we can again derive very

values from here and many questions we

can frame from here okay so very

important data

right okay now you should apply this

kind of funda you should apply this kind

of funda right when we when you say

suppose i want to calculate value of 1

by 23

okay so what is 1 by 23 now so again you

multiply by 100

23 into 4 is 92

8 is left 8 by 23 so again you can sense

here okay if it was 8 by 24 perfectly 1

by 3 that is 0.33

but it is 8 by 23 here that means little

bit more than 8 by 24 that means little

bit more than 0.33 so you can rewrite it

as 4.34

slight less than point slight more than

0.33.34 so it is 1 by 234.34 percent to

the right this kind of approximation you

should understand you should understand

this kind of approximations

okay i hope it is clear this part

okay now come to

next part here

so how to uh derive values from the

table right suppose now i'm writing all

those important values which are used

throughout the quant okay we will find

these numbers throughout the quant every

time okay

and it will be useful table only

so i hope you've written table in the

notebook okay

so see

12 suppose i need to find the value of

what is the

37.5

percentage

of

okay

of

640

so this is our table are you right 37.5

percent special number itself right so

again what is what is the series now you

see 37.5 so you see some you see some

0.5 in this series right you search for

some point five percent test you will

see that one by eight is twelve point

five percentage

right there's a whole series you should

remember just twelve point five series i

say twelve point five then the next

number is three by eight that is thirty

seven point five percent because twelve

point one by eight multiplied by three

so twelve point five multiplied by three

thirty seven point five then five by

eight okay let me write it here

okay because

very important date i am writing here

okay so

since 1 by 8 is 12.5 percent

that means

3 by 8 is

point 37.5 percent

okay what is five by eight

plus

twelve point five into five that is

sixty two point five percent

it is seven by eight

twelve point five into seven that is

87.5

this value should values you should

remember okay so if you remember things

will become very easy 37.5 percent that

means three by eight

three by eight of 640. you cancel it it

it

80 times what is 18 to 3 240

right so it becomes so easy to calculate

value of 37.5 percent of 640 very easy

to calculate the value okay now suppose

18.75 percent of

eighteen point seven five percent of 176

right now looks like a tough question

looks like a tough question is actually

not again if you get defunder from where

does 18.75 percent comes right you

directly see from here on itself okay

that is it is eighteen point seven five

is the half of thirty seven point five

right thirty seven point five half is

eighteen point seven five what is it

39.5 three by eight what is 18.75

percent

half of 3 by 8 that is 3 by 60

so if you get 3 by 16 so you can now

sense it okay 1 by 16 was

6.25 percent

so from here also i can connect

y 1 by 16 was 6.5 because 1 by 8 was

12.5

half of it so 1 by 16 6.25 6.25 into 3

6.25 into 3 is 18.75 percent right into

three so that means it is three by

sixteen so it becomes very easy job

becomes very easy right three by sixteen

into one seventy six you can cancel here

eleven times what is the answer answer

is thirty three such a beautiful

uh numbers these are right to directly

get the fraction value and just solve it

okay

so got to be familiar with this kind of

numbers okay 37.5 18.75 all the numbers

i will write right one by one okay see

how many numbers have covered here so

many numbers 87.5 62.5 37.5

18.75 other than the table right so this

is a very important concept okay now

83.33

of

of

uh 83.33 percent off now let's take any

number take 606.

again looks like a tough question but it

is not what is eighty three point three

three fifteen gonna connect right many

ways to connect eight three point three

three if you remember one by twelve is

eight point three three percent

this is ten eighty three point is 10

times of 8.33 right 10 times 1 by 12 10

times so 10 by 12

10 by 12 is 83.33 percent can cancel 10

by 12 how much it is 5 by 6

5 by 6

therefore

five by six is eighty three point three

three percent

one more thing you can do

right again two is just break this right

eighty three point three three percent

so problem is due to this decimal part

right 0.33 so see in in the table in

table where does 0.33 come in decimal

parts you can see it

33.33

okay so you can break this as you can

break this as 50

plus

33.33 percent

okay

fifty percent plus thirty three point

three three percent

what is fifty percent one by two what is

this one thirty percent one by three one

by two plus one by three how much five

by 6

that is 1 by 2 plus 1 by 3 is what it is

5 by 6

so 5 by 6

right so 5 by 6 is 83.33 percent

okay 5 by 6 is 83.33

what is the answer here

so

this value is ultimately right either

you go by 1 by 12 way or you go by just

breaking by breaking this numbers right

what is the value of 83.33 percent five

by six remain remember it very important

value 83.33

you will see lots of time this because

this kind of numbers in percentage and

and quantity so 5 by 6 of

606 in cancel 1 0 1 times

so 1 0 1 into 5 is what 5 0 5 so 5 0 5

is the answer

right so all these some very nice

numbers we are discussing okay next one

next one

43.75

off

right

43.75 percent of 352.

now what is this 43.75 percent again if

you see here

you can solve this like 43.75

okay

it is like 50 percent

minus 6.25 percent you can break like

this

50 percent is 1 by 2 6.25 is 1 by 16

okay so this is how much this is 7 by

16.

okay one similar number is

56.25 percent

okay so

it is 50

plus 6.25 percent

that is 1 by 2 plus 1 by 16 that is 9 by

16

so two important numbers here right

43.75

and 56.25 percent

right these numbers you'll see

by solving questions further in quant

okay so remember these values

7 by 16 9 by 16 okay so you can simply

solve it now this is how much this is

7 by 16 into 352 resolve it now 16 to

the 32

and 2

22 into 7 20 to 7 142 into 7 14 140 plus

14 154

so this is the answer

right so all these numbers you got to

remember okay now next thing we'll

discuss next thing

next thing will be

multiplying factor okay

multiplying factor

in

percentages

okay what is multiplying factor you see

see all these concepts we are doing and

doing small small problems but very

important problems right whole

percentage

will be used in throughout in profit and

loss sici whole arithmetic mixtures okay

time and distance time and work

everywhere some question numbers also

right everywhere

data interpretation everywhere

percentage is there so for sentence you

understand thoroughly every line you

will listen and you solve these

questions right we'll be doing lots of

good

good coverage of questions good variety

of questions in this okay but what is

multiplying factor right multiplying

factor as a name suggests by what factor

i should multiply

okay

by

what

factor

should we

multiply

this is the meaning of multiplying

factor right multiplying factor

so see here

suppose a number here is

see it will be used it is very useful in

this kind of question suppose

i give you a question 840 is a number

right

you have to decrease

87.5 percent decrease

what is the value

okay so in this kind of question it is

very useful right it's doing multiplying

factor so it is basically

one step up one step up right

one step up miss while solving we can do

that one step in mind and directly can

write and get the answer it will be

faster if you understand this right

see what is multiplying factor now so

if i solve for

it is n point five percent okay so let's

say a number is x let's say a number is

x

i am decreasing 20 percent on x

what is this result can write result as

okay x minus 20 percent of x is what

you'll write normally

x minus 1 by 5 of x

okay this becomes

x into 4 by 5 right and talking about

this x into 4 by 5 this is what i'm

talking about my multiplying factor

sorry my multiplying factor right x to

be decreased by 20

by what factor i should multiply 4 by 5

this is the multiplying factor right

similarly here also

x is decreased by 87.5 percent x is

decreased by

it is n point 5 percent by what factor i

should multiply so what is that 7.5

percent seven by eight so x minus seven

by eight of x i can write the discussion

last flight right it is n point five

percent is what uh uh seven by eight

twelve point five percent one by eight

it's in point five percent seven by

eight so the result result is x into one

by eight

this is my multiplying factor this is my

multiplying factor right by what the

factor i should multiply to get the

result so x being decreased by design

point five percent simply multiply by 1

by 8 so what is the answer here 840

decrease by 87.5 percent simply multiply

by one by eight

so eight eight sixty four so answer is

what answer is eighty sorry not editor

64 i'm sorry is 840 yeah okay

so

it is one zero five

so one zero five is the answer okay so

how to get this quickly okay they get

this funda in mind multiplying factor is

formed by

when you when you

do the operation when you do the

operation with fractions in a question

right suppose

this question so x minus twenty percent

of x so x minus one by five of x right

so i've done the all the operation here

x minus 1 by 5 of x what is 1

x into what is x you get a common so

once you take x as common when you break

this step you take x as common it

becomes 1 minus 1 by 5 right

so

always this x will become as common and

this is always one here also right here

also taken i have skipped this step but

what is it what if i write this step

here this step will look like x you take

common here so if you take x some common

1 minus 7 by 8

okay 1 minus 7 by 8 right

so this is 1 minus 7 by 8. what is the

value here 7 by it this value is 7 by 8

so since decreasing so 1 minus 7 by 8

okay since if it is increasing right if

something is increasing here you can see

if something is increasing for suppose

x is being increased by 25 percent

it's like x plus 1 by 4 of x it's like x

into 1 plus 1 by 4 it's like x into 5 by

4 this 5 by 4 is my multiplying factor 5

by 4 right what is this 1 plus 1 by 4 so

you see here what is 1 by 4 so 1 by 4 is

our

is our

25 value why 1 plus because

it is increasing

here 7 by 8 is our it is 10.5 percent

degrees why 1 minus because it is

decreasing here also what is one by five

one by five is our

twenty percent value why one minus one

by five because

decreasing so always you can we can

generalize it now that

to calculate multiplying factor

so multiplying factor is always

in case of increase

it is 1 plus the fraction value

in case of decrease

it is 1 minus the fraction value

okay so 1 plus fraction value and what

is multiplying factor multiplying factor

okay 1 plus fraction value

and

1 minus fraction value

always right so for one in one step if i

want to write here suppose

if i take example

um

37 point sorry

27 6 uh

648

if decreased by

37.5 percent

what is the result

i should directly write i should

directly write 648 into 5 by 8 is the

answer

and solve it right 8 into 81 but the

answer answer is 4 05 directly i should

do why it now why 8 for fixed 48 into 5

by 8

point because

percent thirty seven point five percent

it is what it is

three by eight degrees for three by

eight degrees what is the multiplying

factor for decrease one minus fraction

value so one minus three by eight that

is 5 by 8 should be the multiplying

factor

right so simply 6 48 into 5 by 8 simply

that's it right

in one step sorry one step solution okay

last slide we did this

okay 840

to be decreased by it is 10.5 percent

think in mind okay what is what is the

fraction value is 7.5 percent seven by

so seven by eight degrees so 840 into

what into

1 minus 4 degrees 1 minus 7 by 8 that is

1 by 8

that's it what is the answer answer is 1

0 5 cancel it 1 0 5

this 1 by 8 is the multiplying factor

right because 7 by 8 degrees means what

again what is multiplying factor seven

by eight degrees one minus seven by

eight is the multiplying factor that is

one by eight

that is one minus fraction value one by

seven by eight right so easy is so so

fast it is

so easy and so fast

okay

now see 1212 when

decreased by decreased by 83.33 percent

i said let's say let's this time

increase by

increase by 83.33 percent what i should

do

one two one two into now what is 83.33

percent fraction value five by six so

five by six increase five by six

increase what is the fraction value of 1

plus 5 by 6 increase so 1 plus fraction

now okay so 1 plus 5 which is 6 that is

11 by 6

11 by 6 okay cancelled 2 0 2 times so 2

0 2 into 11 right as it is 202 into 11

it is

how much tell me 11 22 is 22 and

11 into 20 is what

see 11 you get 2 02 into 11 how you can

break it 200 into 11

sorry 200 into 11 is 2200 and 2 into 11

is 22 so it is 20 to 22

that's it

is the answer right so why 11 by 6 again

same reason because 5 by 6 increase so

this 5 by 6 increase is equal to

multiplying factor of what 1 plus 5 by 6

that is

11 by 6 this is what ln by 6

so increase 1 plus fraction value

decrease 1 minus fraction value

okay

so we'll continue this initial video

thank you

[Music]