Kurikulum Merdeka Matematika Kelas 7 Bab 3 Rasio

Summary

This educational video for 7th-grade students explains the concepts of ratios and scale in a simple and engaging manner. It covers how to compare quantities using ratios, with examples like comparing cups of milk and chocolate, as well as toy robots and cars. The video also introduces the concept of scale, explaining how to use scale ratios to find the actual dimensions of objects. Through practical examples and step-by-step calculations, the lesson ensures students understand these important math concepts, offering clear and relatable explanations throughout.

Takeaways

• 😀 Ratios are comparisons between two quantities and can be written in the form 'a to b'.
• 😀 Ratios should always be simplified to their simplest form, if possible.
• 😀 The order of terms in a ratio must match the order of the quantities being compared.
• 😀 When calculating ratios in word problems, carefully read the problem to identify the correct quantities and their order.
• 😀 The scale is a representation of an object in a reduced or enlarged form without changing its shape.
• 😀 Equivalent ratios have the same value and can be expressed in different forms.
• 😀 In scale problems, multiplication or division can be used to calculate the real-life dimensions from the scaled dimensions.
• 😀 Cross-multiplication is an effective method to solve proportional problems in ratios and scales.
• 😀 For a proportion involving different quantities, the cross-multiplication method helps to find the unknown value.
• 😀 In practical problems like food requirements for animals, the ratio of consumption per animal can help determine the total required amount for a different number of animals.

Q & A

What is a ratio, and how is it represented?

A ratio is a comparison between two quantities, which can be in terms of size or number. It is represented in the form 'a : b', where 'a' is compared to 'b'. For example, '4 : 6' represents a ratio of 4 to 6.

How can we simplify ratios?

Ratios can be simplified by dividing both parts of the ratio by their greatest common divisor. For example, the ratio 4 : 6 can be simplified to 2 : 3 by dividing both 4 and 6 by 2.

Why is the order of elements in a ratio important?

The order of elements in a ratio is important because it should reflect the order in which the quantities are mentioned. For example, if the ratio is 'susu' to 'coklat', it should be written as '4 : 6' rather than '6 : 4'.

How do you find the ratio of toys Andi has?

To find the ratio of robot toys to the total number of toys Andi has, you first determine the number of robot toys (5) and the total number of toys (5 + 10 = 15). Therefore, the ratio is 5 : 15, which simplifies to 1 : 3.

What is the concept of scale in mathematics?

Scale refers to the ratio of the size of an object in a model or diagram compared to its actual size. It involves enlarging or reducing the size of an object while keeping its shape the same.

What does 'equivalent ratios' mean?

Equivalent ratios are ratios that represent the same relationship between two quantities. For example, the ratios 2 : 4 and 3 : 6 are equivalent because both simplify to 1 : 2.

How do you find the missing dimension of a scaled figure?

To find a missing dimension in a scaled figure, use the concept of proportionality. For example, if the original rectangle's length is 16 cm and the scaled figure's length is 32 cm, you can find the scaled width by using the ratio 16 : 32 and applying cross-multiplication.

What method do you use to solve scale problems like the one with rectangles?

In scale problems, you can solve for unknown dimensions by setting up a proportion based on the ratio. For instance, to find the width of a scaled rectangle, you multiply the known dimensions by the scale factor.

How do you solve ratio problems involving multiple quantities?

When solving ratio problems involving multiple quantities, such as the number of rabbits and food required, use cross-multiplication. For example, if 5 rabbits require 60 grams of food, and 8 rabbits are present, the equation 5a = 8 * 60 can be solved to find the amount of food required.

How do you calculate the area of a building from a scaled drawing?

To calculate the area of a building from a scaled drawing, first find the actual dimensions by multiplying the scale by the dimensions on the drawing. Then, convert the dimensions into a consistent unit (such as meters) and calculate the area by multiplying the length and width.