(a)An electronic device which is used to control a chemical process consists of 900 inductors. The cost of replacing an inductor individually is Ksh. 500. The cost of replacing all the inductors is Ksh. 300 per an inductor. The percentage of surviving inductors s(t) at the end of month t is shown in the table below.

Month t

0

1

2

3

4

5

6

s(t)

100

95

84

68

44

22

0

Determine the optimal replacement plan. Comment on your answer