Future value calculation

Misty need to have $15,000 at the end of 5 years in order to fulfill her goal of purchasing a small sailboat. She is willing to invest the funds as a single amount today but wonders what sort of investment return she will need to earn. Use your calculator or the time value tables to figure out the approximate annually compounded rate of return needed in each of these cases:
a. Misty can invest $10,200 today.
b. Misty can invest $8,150 today.
c. Misty can invest $7,150 today.