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 0.40 minute. Complete parts​ (a) through​ (d).

d.) If you select a random sample of 64 customers, there is an 83​% chance that the sample mean is less than how many​ minutes?

Answer 1

solution:

Given that,

mean = = 2.80

standard deviation = = 0.40

n = 64

= 2.80

= / n = 0.40/ 64=0.05

Using standard normal table,

P(Z < z) = 83%

= P(Z < z) = 0.83

z =0.95

Using z-score formula  

= z * +

= 0.95 *0.05+2.80

= 2.8475 minutes

if we rounded this answer so answer will be 3 minutes