SOLUTION: Buddy invested 15000. He put some money in at 4% and remainder in at 5%. At the end of the year he had $690 in interest. How much did he invest at 4% and how much did he invest at

Question 147422: Buddy invested 15000. He put some money in at 4% and remainder in at 5%. At the end of the year he had $690 in interest. How much did he invest at 4% and how much did he invest at 5%?
Found 2 solutions by aswathytony, ej_03:
Answer by aswathytony(47) (Show Source): You can put this solution on YOUR website!
let x be the money buddy invested in 4% interest.
total amount is 15000 . so if x is invested in 4% ; remaining amount invested in 5% interest is 15000 - x
i.e. amount invested for 4% = x
interest on x at 4% = x * 4/100 ........(1)
amount invested for 5% = 15000 - x
interest on 15000 - x at 5% = (15000 - x ) * 5/100 .........(2)
interest at the end of the year = $690
i.e x * 4/100 + (15000 - x )* 5/100 = 690
4x + (15000 - x ) 5 = 690 * 100
4x + 75000 - 5x = 69000
75000 - x = 69000
75000 -69000 = x
i.e x = 6000.
15000- x = 15000 - 6000 = 9000 .

so amount invested for 4% is $6000 & amount invested for 5% is $9000.

Answer by ej_03(8) (Show Source): You can put this solution on YOUR website!
let x=4%
y=5%
eq1 x+y=15000
y=15000=x
eq2 .04x+.05(15000-x)=690
perform the indicated operations in the equation:
.04x+.05(15000-x)=690
.04x+750-.05x=690
.04x-.05x=690-750
.01x/.01=60/.01
x=6000
y=15000-6000=9000
therefore buddy invested 6000 at 4% and 9000 at 5%.
hope this other solution help you through...=)
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