Question

The amount of time a bank teller spends with each customer has a population​ mean, mu​, of 2.80 minutes and a standard​ deviation, sigma​, of 0.50 minute.

b. If you select a random sample of 16 ​customers, there is an 85​% chance that the sample mean is less than how many​ minutes?

Answer 1

Given that,

mean = = 2.80

standard deviation = = 0.50

n = 16

= 2.80

= / n = 0.50 / 16 = 0.125

P(Z < 1.04) = 0.85

z = 1.04

= z * + = 1.04 * 0.50 + 2.80 = 3.32

Answer = 3.32 minutes