Spike142 wrote:139 view so far and yet I am the only one posting...c'mon BTG members please contribute. All you have to do find your favorite PS or DS problem and post it. Help your friends out and warm their brains up for G-Day!
Courtesy of OG review:
Is the following statement sufficient?
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 $120,000
Seriously this took me only like 5 minutes to write...
Nice question there Spike142. Lemme try
lets try to make a equation of the question first.
if each of the first n friends donated 500$ each then, their total would have been 500n
now if each friend persuaded n friends each, the total people referred would become n*n
so the total contribution would be = 500n + 500n*n
now lets take statement 1,
it states that the first group donated 1/16 of the total but we dont have the total so statement 1 alone is INSUFFICIENT
now take statement 2,
The total is given as 120,000$, if we equate this in the equation, we get
500n + 500n*n = 120,000
n + n*n = 240
n*n + n - 240 = 0 , we have a quadratic equation here, so making factors, we get
n*n + 16n - 15n - 240 = 0
n(n + 16) - 15(n + 16) = 0
(n + 16)(n - 15) = 0
n = -16 or 15, since n cannot be negative, we have n = 15
hence using statement 2 alone we can solve the question.
So by the GMAT data sufficiency options, the answer will be
B
hope I am right here :roll: