(Solving for i) (Related to Checkpoint 5.6 on page 176) At what annual interest rate would the following have to be invested?

a. $500 to grow to $1,948.00 in 12 years

b. $300 to grow to $422.10 in 7 years

c. $50 to grow to $280.20 in 20 years

d. $200 to grow to $497.60 in 5 years