ratio prob

d0nw0ng · Posted: Sat Oct 06, 2007 11:49 am Post subject: ratio prob

$60,000 was invested for a year. part of it earned simple annual interest at x percent per yr, and the rest earned simple annual int. at y percent per yr. if the total interest earned by the 60,000 for that yr was 4080, what is x?

1) x = 3y/4
2) the ratio of the amt that earned interest at x% to amt of interest earned at y% is 3:2

arocks · Posted: Sat Oct 06, 2007 12:16 pm Post subject:

To simplify the problem:
Let the amount invested at x% be A. So, 60,000-A is invested at y%
So, A*x%+(60,000-A)*y%=4080

We need to find x. The unknown variables are x,A and y

Stmt1
x=3y/4
This is insuff. No info about A

Stmt2
A/(60,000-A) = 3:2
This is insuff. No info about x and y

Combine stmt1 and stmt2
We will get the value of x. So the answer is C