Lisa deposits $3000 in an account that pays 2% simple interest, and $4000 in a second account which has a higher interest rate but is more risky. What minimum interest rate must she get on the second account in order to earn at least $700 in interest for the year?

Answer 1

just set up the inequality. If the other account has x interest, then

3000(.02) + 4000(x) >= 700
60 + 4000x >= 700
4000x >= 640
x >= 0.16 = 16%