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Problem 2. In an account, interest is credited using a simple interest rate of 5% every year for the first four years. After four years, interest is credited at the force of interest St = t+1/2 1+t+t, t 4. The following values are numerically equal: The current value at time t = at time t = 7. 4 of payments of 1,000 at time t = 2 and 400 The present value at time t = 0 of payment of X at time t = 10. Calculate X