15. Assume that x has a normal distribution with the specified mean and standard deviations.

15.  Assume that x has a normal distribution with the specified mean and standard deviations.  Find the indicated probabilities.

a. P (2.9<=x<=5) mean = 3 and standard deviation= 2.2

Use the following information to answer parts b and c. Explain the meaning of the probabilities in the context of this problem.

The length of life of a certain type of refrigerator is approximately normally distributed with a mean of 4.8 years and a standard deviation of 1.3 years.

b. If the appliance is guaranteed for two years, what is the probability that a refrigerator of this type would require replacement under the guarantee?

c. What is the probability that a refrigerator of this type chosen at random will last between 5 and 6 years?