Question: A manufacturer of electronics products expects that 1% of units fail during the warranty period. A sample of 400 independent units is tracked for warranty performance.

a) What is the expected number of failures during the warranty period?

b) What is the probability that none fails during the warranty period?

c) What is the probability that more than five units fail during the warranty period?

d) What is the probability that the number of failures will be between one standard deviation of the mean value?