Insulators produced by a factory have a breakdown voltage distribution that can be approximated by a normal distribution. The coefficient of variation is 5%. a) What is the smallest sample size that...

Insulators produced by a factory have a breakdown voltage distribution that can be approximated by a normal distribution. The coefficient of variation is 5%.

a) What is the smallest sample size that will ensure a probability of 90% that the sample mean measured is within 2% of the population mean? The samples are taken randomly.

b) If economic reasons dictate that the sample size should be 40, what is now the confidence level associated with the sample mean lying within 2% of the population mean?

c) What is the probability that an insulator will have a breakdown voltage 10% higher than the mean breakdown voltage?