5.85 A company services home air conditioners. It is known that times for service calls follow a normal distribution with a mean of 60 minutes and a standard deviation of 10 minutes.

a. What is the probability that a single service call takes more than 65 minutes?

b. What is the probability that a single service call takes between 50 and 70 minutes?

c. The probability is 0.025 that a single service call takes more than how many minutes?

d. Find the shortest range of times that includes 50%

of all service calls.

e. A random sample of four service calls is taken.

What is the probability that exactly two of them take more than 65 minutes?