Concepts discussed on September 23, 2017
Logical Reasoning Venn Diagrams Part 2
Welcome to the live session of Logical Reasoning Venn Diagrams Part 2 . The concepts and questions discussed on September 23, 2017 during the live session follow the embedded video. The video link next to each concept will take you to the start of the part of the video where that specific concept is discussed. Click the video embedded below to watch the entire session.

How many students have only Pencil and Eraser?

How many students have Pencil, Marker & Eraser?

How many students have Pencil?
Students in a classroom
In a classroom of 100 students, students have pens, pencils, markers and erasers. No student has a pen and a pencil because they need to have one writing device for writing on paper. 30 students have exactly three out of the four things, 25 students have exactly two out of the four things. 49 students have eraser, 3 more than the number who have markers and 6 more than the number who have pens. 20 have only pens, while only 3 have only erasers. 75 students have an odd number of objects.
Number of students who have pen and marker only is one more than the number who have marker and pencil only and one less than the number who have pen and eraser only.
The number of students who have marker and pencil only is the arithmetic mean of number who have marker and eraser only and the number who have pen and eraser only.

What is the minimum number of students who could have said that only Quant was their weakest section prior to the exam?

What is the minimum number of students who could have said that all three sections were easier than they had feared post the CAT?

What is the maximum number of students who could have said that only verbal was their weaker section prior to the exam?

We know that 220 students had said that Quant and VARC were their weaker sections, how many felt that DILR was the only section they were weak in prior to the exam?
All about CAT
Article from 2IIM website, dated Nov 27th 2017.
1000 people were surveyed prior to CAT on what they thought was their weaker section(s). Around 535 said it was Quant, 625 said DILR and 420 said it was VARC. Turns out the respondents were smart, understood the question clearly and no one said that all three were their weaker section; nor did anyone say he/she had no weaker section.
The same thousand were surveyed at the end of the exam and asked which section(s) was tougher than how they thought it would be – some 260 said it was Quant, 180 said it was DILR and 230 said it was VARC. A few said that all three were tougher than expected and a few also said that none of the three was tougher than expected.
Turns out some of the responses were mere reflections of the states of mind of students. For instance, 25% of the students who thought of more than one section to be their weakest found all three sections to be tough, while among the ones who thought only one section would be tough none found all three tough.
The number of students who had thought of Quant and DI as their weak sections prior to the exam was twice the number who had thought of DI and VARC as their weaker sections prior to the exam.
Number of students who thought of Quant and VARC as their weak sections is greater than the number who thought of DI and VARC as their weaker sections and lesser than the number who thought of DI and Quant as their weaker sections.