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

Redeem

In the interior of a forest, a certain number of apes equal

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Master | Next Rank: 500 Posts
Posts: 421
Joined: Sun Apr 17, 2011 4:27 am
Location: India
Thanked: 6 times
Followed by:2 members
GMAT Score:620

In the interior of a forest, a certain number of apes equal

by vinni.k » Thu Jan 09, 2014 8:18 am
In the interior of a forest, a certain number of apes equal to the square of one-eighth of the total number are playing and having great fun. The remaining twelve apes are on a hill and the echo of their shrieks by the adjoining hills frightens them. They came and join the apes in the forest and play with enthusiasm. What is the total number of apes?

A. 48

B. 16

C. 64

D. 80

E. 16 or 48

OA is E

How to create the right equation, not matching with my equation.

Thanks & Regards
Vinni
Top
Source: — Problem Solving |
User avatar
Master | Next Rank: 500 Posts
Posts: 490
Joined: Thu Jul 04, 2013 7:30 am
Location: Chennai, India
Thanked: 83 times
Followed by:5 members

by Uva@90 » Thu Jan 09, 2014 9:00 am
Hi Vinni,
Total # of Apes = (x/8)^2 +12
where x is the total number of apes playing and having great fun.

since x and Total # are number of apes they must of integer.

1^2+12 =13
2^2+12 =16
3^2+12 =23
4^2+12 =28
5^2+12 =37
6^2+12 =48
7^2+12 =61
8^2+12 =76
9^2+12 =93

Only the green color highlighted one are in the options.

Hence Ans is E

Regards,
Uva.
Known is a drop Unknown is an Ocean
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Thu Jan 09, 2014 11:36 am
The question stem should read as follows:
vinni.k wrote:In the interior of a forest, a certain number of apes equal to the square of one-eighth of the total number are playing and having great fun. The remaining twelve apes are on a hill and the echo of their shrieks by the adjoining hills frightens them. They came and join the apes in the forest and play with enthusiasm. Which of the following includes every possible value for the total number of apes?

A. 48

B. 16

C. 64

D. 80

E. 16 or 48
We can plug in the answers, which represent the total number of apes.

The square of one-eighth of the total number are playing and having great fun.
The remaining twelve apes are on a hill.

Answer choice A: 48 apes
Here, the number playing = (48/8)² = 36, implying that the number on the hill = 48-36 = 12.
This works.
Eliminate B, C, and D.

Answer choice E: 16 or 48 apes
If there are 16 apes, the number playing = (16/8)² = 4, implying that the number on the hill = 16-4 = 12.
This also works.
Eliminate A.

The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
User avatar
Master | Next Rank: 500 Posts
Posts: 421
Joined: Sun Apr 17, 2011 4:27 am
Location: India
Thanked: 6 times
Followed by:2 members
GMAT Score:620

by vinni.k » Sat Jan 11, 2014 8:28 am
Thank you.
Top
GMAT Instructor
Posts: 2630
Joined: Wed Sep 12, 2012 3:32 pm
Location: East Bay all the way
Thanked: 625 times
Followed by:119 members
GMAT Score:780

by Matt@VeritasPrep » Sun Jan 12, 2014 6:22 pm
Great question! For fun and further practice, here's a follow up from the famous Lilavati, a 12th century Indian math text (as you can see, these sort of questions have been around forever):

Out of a group of swans, 7/2 times the square root of the number are playing on the shore of a pond. The two remaining ones are fighting in the water. What is the total number of swans?
Top
Master | Next Rank: 500 Posts
Posts: 468
Joined: Mon Jul 25, 2011 10:20 pm
Thanked: 29 times
Followed by:4 members

by vipulgoyal » Sun Jan 12, 2014 9:03 pm
T-(t/8)^2=12
T^2 - 64T + 768 = 0
(t-48)(t-16)=o
t= 48,16
Top
Post new topic Post Reply
• Page 1 of 1