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

Redeem

Mary persuaded n friends

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 200
Joined: Thu Aug 07, 2008 5:14 pm
Thanked: 1 times

Mary persuaded n friends

by ska7945 » Sat Aug 23, 2008 6:53 pm
Mary persuaded n friends to donate $500 each to her election campaign, and then each of these n friends persuaded n more people to donate $500 each to Mary’s campaign. If no one donated more than once and if there were no other donations, what was the value of n?
(1) The first n people donated 1/16 of the total amount donated.
(2) The total amount donated was $120,000.



oa D
let's beat GMAT.
Top
Source: — Data Sufficiency |
Junior | Next Rank: 30 Posts
Posts: 14
Joined: Fri Aug 22, 2008 9:51 pm
Thanked: 3 times

by carefreeamit » Sun Aug 24, 2008 10:22 pm
I got answer as D.

If Mary persuaded n friends and they in turn persuaded n friends each
then
in the first round total collected was = 500 * n
In the second round total collected was = 500 * n^2
Total collection = 500(n + n^2)

Option a
First round collection/total collection = 1/16
(500n)/500(n + n^2) = 1/16
n/n(1 + n) = 1/16
1+ n = 16
n = 15
sufficient

option b
500 * (n + n^2) = 120000
n^2 + n - 240 = 0
(n + 16) (n - 15) = 0
n = 15
sufficient

Ans D
Top
Post new topic Post Reply
• Page 1 of 1