The average number of units which the factory workers at Shilo Company assemble per week is µ = 45 with standard deviation of s = 12. Suppose that the distribution of units assembled is normal. If a sample n = 25 were drawn from all of the workers,
a. What range of units manufactured through this sample would contain sample mean 90% of time? Hint: Find out the middle 90% of the distribution of sample means.