BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

A certain high school (OG13)

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 435
Joined: Wed Nov 16, 2011 7:27 am
Thanked: 48 times
Followed by:16 members

A certain high school (OG13)

by alex.gellatly » Thu Aug 02, 2012 9:45 pm
A certain high school with a total enrollment of
900 students held a science fair for three days last
week. How many of the students enrolled in the high
school attended the science fair on all three days?
(1) Of the students enrolled in the school,
30 percent attended the science fair on two
or more days.
(2) Of the students enrolled in the school,
10 percent of those that attended the science
fair on at least one day attended on all three
days.
A useful website I found that has every quant OG video explanation:

https://www.beatthegmat.com/useful-websi ... tml#475231
Top
Source: — Data Sufficiency |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3835
Joined: Fri Apr 02, 2010 10:00 pm
Location: Milpitas, CA
Thanked: 1854 times
Followed by:523 members
GMAT Score:770

by Anurag@Gurome » Thu Aug 02, 2012 9:59 pm
alex.gellatly wrote:A certain high school with a total enrollment of
900 students held a science fair for three days last
week. How many of the students enrolled in the high
school attended the science fair on all three days?
(1) Of the students enrolled in the school,
30 percent attended the science fair on two
or more days.
(2) Of the students enrolled in the school,
10 percent of those that attended the science
fair on at least one day attended on all three
days.
According to the given information, there can be number of students, who didn't attended the fair.

So, following cases can be possible:

A. Students who attended on only one day
B. Students who attended on two days exactly
C. Students who attended on all three days
D. Students who did not attended the fair

So, A + B + C + D = 900. We have to find C.

(1) 30% of 900 attended 2 or more days implies 0.30 * 900 = 270 attended 2 or more days.
B + C = 270; Not SUFFICIENT.

(2) 10 percent of those that attended the science fair on at least one day attended on all three days implies 10% * (A + B + C)= C
A + B = 9C; Not SUFFICIENT.

Combining (1) and (2), B + C = 270, A + B = 9C and A + B + C + D = 900.
We have 3 equations, 4 unknowns; Not SUFFICIENT.

The correct answer is E.
Anurag Mairal, Ph.D., MBA
GMAT Expert, Admissions and Career Guidance
Gurome, Inc.
1-800-566-4043 (USA)

Join Our Facebook Groups
GMAT with Gurome
https://www.facebook.com/groups/272466352793633/
Admissions with Gurome
https://www.facebook.com/groups/461459690536574/
Career Advising with Gurome
https://www.facebook.com/groups/360435787349781/
Top
Post new topic Post Reply
• Page 1 of 1