Of the 720 students at a certain university, 25 percent are seniors.

Question

Of the 720 students at a certain university, 25 percent are seniors. If x seniors were to graduate early and leave the university and no additional students entered or left the university, what value of x would reduce the number of seniors at the university to 20 percent?

(A) 30
(B) 36
(C) 42
(D) 45
(E) 48

Are You Up For the Challenge: 700 Level Questions

(A) 30
(B) 36
(C) 42
(D) 45
(E) 48

Are You Up For the Challenge: 700 Level Questions

Shriyaverma19 · Answer

25% of 720= 180

20=(180-x\720-x ) 100
Solve for x you get x= 45

IMO option D is correct

firas92 · Answer

Number of Seniors =  \frac{720}{4} = 180

\frac{180-x}{720-x}=\frac{1}{5}

900-5x=720-x

x=45

Answer is  (D)

nick1816 · Answer

Number of seniors= 720/4=180

\frac{180-x}{720-x}= \frac{1}{5}

900-5x=720-x
180=4x
x=45

Kinshook · Answer

Given: 
1. Of the 720 students at a certain university, 25 percent are seniors. 
2. x seniors were to graduate early and leave the university and no additional students entered or left the university

Asked: What value of x would reduce the number of seniors at the university to 20 percent?

1. Of the 720 students at a certain university, 25 percent are seniors. 
Total students = 720
Seniors = 25% *720 = 180

2. x seniors were to graduate early and leave the university and no additional students entered or left the university

What value of x would reduce the number of seniors at the university to 20 percent?
Total students left = 720 - x
Seniors left = 180-x
Percentage of seniors = .2(720 - x) = 180 -x
144 - .2x = 180 - x
.8x = 36
x = 36/.8 = 360/8 = 45

IMO D

HarshavardhanR · Answer

Number of students = 720
Number of seniors = 25% of x = 1/4 of 720 = 180.
Number of seniors who left = x
Number of seniors remaining = 180 - x
Number of students remaining = 720 - x

For what x is the number of remaining seniors 20%?

i.e.,

180 - x = 20% of (720 - x) = (1/5) (720 - x)

=> x = 45. Choice D.

Harsha
GMAT Tutor | gmatanchor.com

Of the 720 students at a certain university, 25 percent are seniors.

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