gmat paper test code 28 section 5 q11 ( ratio problem)

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In certain calculus class, the ratio of the number of mathematics majors to the number of students who are not mathematics majors is 2 to 3. if 2 more mathematics majors were to enter the class , the ratio would be 1 to 2, How many students in the class ?

A)10
B)12
C)21
D)28
E)35
answer is 28 .
but I doubt about the correctness of question. How come etc copywrite material of cost of 25$ be wrong. please confirm it whether it is wrong or not.

my stragedy to solve is below

2X+2/3X=1/2
4X+4=3X
-ve value of X how come ?


a

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by AleksandrM » Wed Apr 30, 2008 9:13 am
This question seems wrong. The set-up should be as follows:

2/3 = m/n and m + 2/n = 1/2

When you try to solve the problem using this approach, which is supposed to work, you end up with negative values.

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by netigen » Wed Apr 30, 2008 11:39 am
The Q is wrong because the total should be divisible by 5 for the ratios to be 2:3 so the answer can not be 28

Furthermore, if the current ratio of math students is 2/3 = 0.666 than when you add 2 more maths majors the ratio will go up and not down to 1/2 = 0.5