What steps do I take to calculate :the personnel office at a large electronics firm regularly schedules job interviews and maintains records of the interviews. From the past records, they have found that the length of a first interview is normally distributed, with mean μ = 39 minutes and standard deviation σ = 6 minutes. (Round your answers to four decimal places.)
(a) What is the probability that a first interview will last 40 minutes or longer?
(b) Sixteen first interviews are usually scheduled per day. What is the probability that the average length of time for the sixteen interviews will be 40 minutes or longer? I really need to understand the specific steps, not just the formula. Also is there a way to calculate using Excel, or an online calculator? You can even use different numbers, I just really need to understand the steps. Thank you!!