Problema Solution
Last year, Frank had $10,000 to invest. He invested some of it in an account that paid 7% simple interest per year, and he invested the rest in an account that paid 8% simple interest per year. After one year, he received a total of $710 in interest. How much did he invest in each account?
Answer provided by our tutors
let x be the amount he invested in the 7% account & y be the amount he invested in the 8% account. set up 2 equations:
x + y = 10000
.07x + .08y = 710
solve for x in the first
x = 10000 - y
substitute this into the second
.07(10000-y) + .08y = 710
700 - .07y + .08y = 710
700 + .01y = 710
.01y = 10
y = 1000
and x = 10000 - y = 10000 - 1000 = 9000
so he invested $9000 in the account with 7% interest and $1000 in the account with 8% interest