Scott Woodbury-Stewart

GMAT OFFICIAL GUIDE PS – A certain experimental mathematics program was tried out in 2 classes…

A certain experimental mathematics program was tried out in 2 classes…

Solution:

We are given that a certain experimental mathematics program was tried out in 2 classes in each of 32 elementary schools and involved 37 teachers. Thus, there were a total of 2 x 32 = 64 classes under this program.

If we let a = the number of teachers teaching one class, b = the number of teachers teaching two classes, and c = the number of teachers teaching 3 classes, we can create the following equations:

a + b + c = 37

a + 2b + 3c = 64

Subtracting equation 1 from equation 2, we have:

(a + 2b + 3c = 64) – (a + b + c = 37)

b + 2c = 27

2c = 27 – b

c = (27 – b)/2

We see that c is the GREATEST when b = 1, and thus (27 – 1)/2 = 26/2 = 13.

We also see that c is the LEAST when b = 27, and thus (27 – 27)/2 = 0/2 = 0.

So the range of values of n is 0 to 13.

Answer: A

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