Suppose that the average time before breakdown is normally distributed with a mean of 3 weeks and a standard deviation of 0.2 weeks. If breakdowns cost an average of $1,500 and preventive maintenance costs $1,000, what is the optimal maintenance interval?

Select one:

a. 1.83 weeks

b. 2.40 weeks

c. 2.83 weeks

d. 2.29 weeks

e. 2.95 weeks

f. 2.08 weeks