If you have 7.00 now and 8.10 in 3 years what is the effective annual interest rate?

Assuming no withdrawals out or deposits into the contract, the answer is determined as follows:

7.00 x (1+i)^3 = 8.10 (now we solve for i)

i = (8.10/7.00)^(1/3)-1

i = 4.9854%