If 37.5% of the 880 students at a certain college...

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swerve: Legendary Member; Posts: 2499; Joined: Sun Oct 29, 2017 2:04 pm; Followed by:6 members

If 37.5% of the 880 students at a certain college...

by swerve » Tue Jan 02, 2018 6:34 am

If 37.5% of the 880 students at a certain college are enrolled in biology classes, how many students at the college are NOT enrolled in a biology class?

A. 110
B. 330
C. 550
D. 430
E. 880

The OA is C.

Please, can any expert explain this PS question for me? I tried to solve it but I can't get the correct answer. I need your help. Thanks.

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Source: Beat The GMAT — Problem Solving | Tue Jan 02, 2018 6:34 am

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pm; Location: Vancouver, BC; Thanked: 5254 times; Followed by:1268 members; GMAT Score:770

by Brent@GMATPrepNow » Tue Jan 02, 2018 7:25 am

swerve wrote:If 37.5% of the 880 students at a certain college are enrolled in biology classes, how many students at the college are NOT enrolled in a biology class?

A. 110
B. 330
C. 550
D. 430
E. 880

37.5% = 3/8
So, we can say: 3/8 of the 880 students at a certain college ARE enrolled in biology classes
This means 5/8 of the 880 students at a certain college are NOT enrolled in biology classes

5/8 of 880 = (5/8)(880) = 550
Answer: C

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

Quote

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pm; Location: Vancouver, BC; Thanked: 5254 times; Followed by:1268 members; GMAT Score:770

by Brent@GMATPrepNow » Tue Jan 02, 2018 7:27 am

swerve wrote:If 37.5% of the 880 students at a certain college are enrolled in biology classes, how many students at the college are NOT enrolled in a biology class?

A. 110
B. 330
C. 550
D. 430
E. 880

We can actually solve this question without doing any calculations. Instead, we'll just use a little number sense.

37.5% is less than 1/2.
So, if LESS THAN half of the 880 students ARE enrolled in biology, we can conclude that MORE THAN half of the 880 students are NOT enrolled in biology.
Half of 880 is 440, so we're looking for an answer choice that's GREATER THAN 440

This leaves C or E.
Of course, E makes no sense, so the correct answer must be C

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

Quote

GMAT/MBA Expert

[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pm; Location: Palo Alto, CA; Thanked: 2867 times; Followed by:511 members; GMAT Score:800

by [email protected] » Tue Jan 02, 2018 12:08 pm

Hi swerve,

We're told that 37.5% of the 880 students at a certain college are enrolled in biology classes. We're asked for the number of students at the college are NOT enrolled in a biology class. The answer choices to this question are 'spread out' enough that we can answer it with estimation.

37.5% can be 'rounded' to 1/3
880 can be 'rounded' to 900

1/3 of 900 is 300, so approximately 300 of the students are enrolled in biology classes. This means that 880 - 300 = 580 are NOT enrolled in biology classes. There's only one answer that's close to 580...

Final Answer: C

GMAT assassins aren't born, they're made,
Rich

Contact Rich at [email protected]

Quote

GMAT/MBA Expert

Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Mon Sep 02, 2019 6:12 pm

swerve wrote:If 37.5% of the 880 students at a certain college are enrolled in biology classes, how many students at the college are NOT enrolled in a biology class?

A. 110
B. 330
C. 550
D. 430
E. 880

The OA is C.

Please, can any expert explain this PS question for me? I tried to solve it but I can't get the correct answer. I need your help. Thanks.

Since 37.5% = 3/8, 3/8 of the 880 students are enrolled in biology classes. That means 5/8 of the students or 5/8 x 880 = 5 x 110 = 550 students are not.

Answer: C

Scott Woodbury-Stewart
Founder and CEO
[email protected]