M7MBA wrote: ↑

Thu Jul 22, 2021 7:19 am

How many of the 42 people in a group are employed students?

(1) 29 of the 42 people are employed.
(2) 24 of the 42 people are students.

Answer: E

Source: GMAT Prep

Here's a step-by-step approach using the Double Matrix method.

Here, the criteria are:
- employment status (employed or unemployed)
- schooling (student or non-student)

There are 42 people altogether, so our first diagram looks like this:


Notice that I placed a star in the top-left box. The target question asks us to determine the number of people in this box.

Statement 1: 29 out of 42 are employed.
We get:

Since we cannot find the number of people in the top-left box, statement 1 is NOT SUFFICIENT

Statement : 24 out of 42 are students.
We get:

Since we cannot find the number of people in the top-left box, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined:
We get:

Since we still cannot find the number of people in the top-left box, the combined statements are NOT SUFFICIENT

Answer: E