Please solve step by step using formula manually not using excel. Thank you.

Question 1 The force of interest is defined as follows, 3 8(t) 4(1 + t)' t> 0 with t representing the time of the investment period from the beginning of investment. By using the given force of interest, answer the following questions:- (a) Write the accumulated value of 1 unit investment fund from time t to tu. (b) Compute the interest rate for the fourth year, iq. (c) Compute the present value of sum of the payments of RM100 made at the end of second year and RM300 made at the end of fourth year. (d) If RM200 and RM400 are respectively deposited initially and at the end of second year, compute the amount of return for the fifth year, 15