An expensive watch is powered by a 3-volt lithium battery expected to last four years. Suppose the life of the battery has a standard deviation of0.7 year and is normally distributed.

a. Determine the probability that the watch's battery will last longer than

4.4

years.

b. Calculate the probability that the watch's battery will last more than

3.35

years.

c. Compute the length-of-life value for which

20%

of the watch's batteries last longer.