Question

Sam is a night watchman in a large warehouse. During one complete round of the warehouse, he must check in at 40 different checkpoints, all of which are about the same distance apart. At each checkpoint he inserts a key that tells a central computer the time he checked in. Let x be a random variable representing the length of time from one check-in to the next. While monitoring Sams check-in times for the past year, the computer found the mean of the x distribution to be µ = 6.2 minutes with standard deviation s = 1.7 minutes. In two complete rounds of the warehouse, there are 80 check-in time intervals. What is the probability that the average check-in time interval will be from 6 to 7 minutes?

Answer 1

Refer Standard normal table/Z-table to find the probability or use excel formula "=NORM.S.DIST(4.21, TRUE)" & "=NORM.S.DIST(-1.05, TRUE)" to find the probability.