Curso completo de Raciocínio Lógico para Concursos Público 2019 - Aula 06

Summary

This educational video script delves into the concept of logical diagrams, emphasizing their importance in competitive exams. It explains set operations such as union, intersection, and complementarity, using relatable examples like lawyers and bankers to clarify. The script also includes practical exercises to reinforce understanding, illustrating how to calculate the total number of students using different study methods and how to interpret bibliographic references for a public exam. The lesson aims to ensure candidates are well-prepared and confident in tackling logical set operations.

Takeaways

• 📚 The lecture focuses on 'logical diagrams', a common topic in various competitive exams, emphasizing the importance of understanding these diagrams for success.
• 🔗 Logical diagrams are intrinsically linked to set theory and operations with sets, which is why a review of basic set operations is suggested as a foundation.
• 👥 The concept of 'union' in sets is explained with an example involving lawyers and bankers, highlighting that 'or' in this context means 'one or the other or both'.
• 🤝 The 'intersection' of sets is discussed, using the example of people who are both lawyers and bankers, to clarify the difference between 'and' and 'or' in set theory.
• 👨‍💼 The script distinguishes between 'only lawyers', 'only bankers', and 'only lawyers or bankers', explaining how to represent these subsets in logical diagrams.
• ❌ The concept of 'complement' is introduced, relating it to the idea of 'not', and explaining how to represent the set of people who are neither lawyers nor bankers.
• 📈 The importance of understanding the relationship between the number of elements in the union and intersection of sets is highlighted, with a practical example involving students and their study methods.
• 📊 A detailed example is provided to illustrate how to calculate the total number of students using different study methods by correctly accounting for overlaps and unique groups.
• 📚 An example involving books recommended for a public competition exam is used to demonstrate how to determine the number of candidates who read different combinations of books.
• 📘 The script clarifies the difference between using 'or' to include any combination of attributes and 'only' to specify exclusivity, as seen in the book example.
• 📝 The importance of practicing with exercises is emphasized to consolidate understanding of logical diagrams and set operations.

Q & A

What is the main topic of the web class?

The main topic of the web class is logical diagrams, which are common in many competitive exams.

Why is it important to be focused on logical diagrams?

It is important to be focused on logical diagrams because they are easy, and neglecting them could result in losing a sure-shot question in exams.

How are logical diagrams related to sets?

Logical diagrams are intrinsically linked to operations with sets, such as union, intersection, and difference.

What does the union of two sets represent?

The union of two sets represents all elements that are in either set or both sets.

How is the intersection of two sets different from their union?

The intersection of two sets includes only the elements that are present in both sets simultaneously.

What does 'only lawyers' mean in the context of sets?

'Only lawyers' refers to the set of people who are lawyers but not bankers.

What is meant by the complement of a set?

The complement of a set includes all elements that are not in the given set, within the universal set being considered.

How do you calculate the total number of elements in the union of two sets?

The total number of elements in the union of two sets is the sum of the number of elements in each set minus the number of elements in their intersection.

In the example of students attending different types of classes, how many students attended only video classes?

In the example, 50 students attended only video classes.

What should you do when working with three sets in a logical diagram?

When working with three sets, it is important to consider all possible intersections and unions among the sets, ensuring clarity in the relationships and overlaps between them.