At Veridux Corporation, there are 250 employees. Of these, 90 are fema

MAGOOSH OFFICIAL SOLUTION

I will demonstrate the Double Matrix Method first by solving question #1, then question #2. In the Double Matrix Method, you make a sectioned box, a rectangle with subdivisions. The horizontal subdivisions will represent the categories of one variable, and the vertical subdivisions will represent the categories of the other variable. Here’s the set-up for question #1: I temporarily put letters in the boxes, to facilitate talking about those boxes.

A is number of male managers, B is the number of female managers, and A + B = C is the total number of managers. Similarly, D is the number male associates, and A + D = G is the total number of males. In any row, you can add across the first two boxes and the sum will be the box on the right. In any column, you can add the top two boxes, and the sum will be the bottom box. The final number, I, is the “grand total”, the total number of employees in the whole problem, which obvious has to equal the sum of males + females, as well as the sum of managers + associates.

Here’s that matrix again with the numbers from the problem filled in — just the numbers stated in black-and-white in the problem.

Well, first let’s take care of the “totals”. The numbers in the “totals” row must add up. If 90 are females, the other 250 – 90 = 160 must be males. Similarly, the numbers in the “totals” column must add up. If 40 are managers, then the other 250 – 40 = 210 must be associates.

Now, in the “associate” row, 135 + E = 210, which means E = 75 — the other 75 associates must be female.

Now, to find B, which is what the question is asking, we need only look at the sum in the “female” column: B + 75 = 90, which means B = 15. There are fifteen female managers in this company. Thus, the answer = (A).

Instead of this route, once we found all the “totals” numbers, we could have used addition in the “male” column to find A = 25, then use addition across the “managers” to find B = 15 —- in fact, if you have a second route for finding the number, you should perform that too, to verify that you get the same number both ways.

- See more at: https://magoosh.com/gmat/2012/gmat-sets- ... XxtSw.dpuf

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