The average time before breakdown of a machine is normally distributed and has a mean of 9 weeks and a standard deviation of 1.5 weeks. If breakdown cost averages $2,500 and preventive maintenance costs $500,

The ratio of preventive cost to the sum of preventive and breakdown cost is:

Select one:

a. 0.167

b. 200

c. 0.267

d. 100

e. 0.345