Couldn’t convert “each of these n friends persuaded….”line in an equation.
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.
Hi Ria,
Whenever you find difficulty in constructing the equation. Always start plugging in.
If n = 2,
Total amount first stage is 1000.
And these 2 people persuade another 2 people each, so there are 4 people totally the persuaded. So total amount is 2000 in second stage.
So that’s all, you can understand that, if n people in first stage, then n^2 people in second stage.
The number of people donated at the first stage – n, So, total amount – 500n;
The number of people donated at the second – n^2, So, total amount – 500n^2;
Total amount donated – 500n+500n^2
(1) The first n people donated 1/16 of the total amount donated .
16(500n)=500n+500n^2 . “n” has to be positive.
n=15.
Sufficient.
(2) The total amount donated was $120,000. “n” has to be positive.
500n+500n^2=120,000
n=15. Again “n” is positive.
Sufficient.
So the answer is D.
