An expensive watch is powered by a 3- volt lithium battery expected to last three years. Suppose the life of the battery has a standard deviation of 0.7 year and is normally distributed.

a. Determine the probability that the watch's battery will last longer than 3.2 years.

b. Calculate the probability that the watch's battery will last more than 2.75 years

c. Compute the length of life value for which 15% of the watch's batteries last longer