Bill and Joe each put 30 into separate accounts at time t = 0, where t is measured in years Bill's account earns interest at a constant annual effective interest rate of K/ 100, K > 0. Joe's account earns interest at a force of interest, og = 1/(K + 0.4t). At the end of five years, the amount in each account is X. Calculate X. 38.7 45.1 51.9 56.4 58.1