An answer to this question

Question

a college student earned $9,000 during summer vacation working as a water in a popular restaurant the student invested part of the money at 9% and the rest at 8% if the student received a total of $760 in interest at the end of the year how much was invested 9%

Answer 1

amount invested at 9% is $4,000.

09x + .08(9-x) = .760 where x=amount invested at 9%.. 9%=.09, 8%=.08, .760 thousand =$760 interest, numbers are in units of thousands

.09x -.08x = .76 -.72

.01x = .04

x = .04/.01 =4 thousand dollars

= $4000 invested at 9%

and 9-4= $5000 invested at 8%

check the answer

.09(4000) + .08(5000)

= 360 + 400 = 760

760/9000 =76/900= 19/225 =0.08444... = 8 4/9%= average return on the $9000

9-8 4/9 = 5/9

8 4/9 -8 = 4/9

5/9/4/9 =5/4 = 1.2

1.2 times as much is invested at 8% as at 9%

1.2 times x = 9-x

1.2(4)=5