Sandra Enright of Techtronics Inc., an electronics supply firm, has been examining the times required for stock pickers to fill orders requested from inventory. She has determined that individual order-filling times approximately follow a normal distribution with a mean value of 3.9 minutes and standard deviation of 78 seconds.
a) What is the probability that a randomly selected order will require more than three minutes?
b) What is the probability that a randomly selected order will require less than two minutes?
c) What is the probability that a randomly selected order will require between two and three minutes?
d) Sandra is considering a quality assurance that 95% of orders will be filled within a specified time. What time should she specify?