AAPL wrote:GMAT Prep

In a certain senior class, 72 percent of the male students and 80 percent of the female students have applied to college. What fraction of the students in the class are male?

1) There are 840 students in the senior class.
2) 75 percent of the students in the senior class have applied to college.

OA B

Say there are x numbers of male and y numbers of female students.

Thus, we have

# of students who have students have applied to college = 72% of x + 80% of y = 0.72x + 0.80y

We have to get the value of x/(x + y).

Let's take each statement one by one.

1) There are 840 students in the senior class.

=> x + y = 840. Can't get the value of x/(x + y). Insufficient.

2) 75 percent of the students in the senior class have applied to college.

=> 0.72x + 0.80y = 75% of (x + y)
0.72x + 0.80y = 0.75% x + 0.75y

x = 5y/3

Thus, the required fraction = x / (x + y) = (5y/3) / (5y/3 + y);

y gets canceled, and we get a unique answer. Sufficient.

The correct answer: B

Hope this helps!

-Jay
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