Some auto companies design emission sensors so that they must be replaced after 100,000 miles.One such company found that the service life (in months) of these sensors is normally distributed with a mean of 48 months and standard deviation of 9 months.The company decided to replace sensors in the bottom 5% of service life.What should be the length (in months) of the guarantee?

The company decided to replace sensors in the bottom 5% of service life. What should be the length (in months) of the guarantee? Round your answer to the nearest whole month.

a) 25 months

b) 27 months

c) 30 months

d) 33 months