The life of a watch battery is normally distributed with a mean of 950 days and a standard deviation of 40 days. Using the appropriate Excel functions, determine the following .

a) What fraction of batteries is expected to survive beyond 1010 days?

b) What fraction will survive a fewer than 900 days?

c) Draw a graph of the reliability function using Excel?

d) What Length of warranty is needed so that no more than 10% of the batteries can be expected to fail during the warranty period?