Answer:
The answer is on the attachment.
Basically, the frog only jumps two feet every time, so he would need 8 jumps, because there was still that extra 1/2 of a foot.
(1+R) to the power of n = A/P
(1+R) to the power of 4 = 3238.17/2600
(1+R) to the power of 4 = 1.245
(1+R) = 4 root 1.245
1+r = 1.05631
R = 0.05631
The interest rate percentage is 5.63% (2dp)