Question

The owners of an eyeglass store claim that they fill customers' orders, on average, in 60 minutes with a standard deviation of 15.9 minutes. Based on a random sample of 40 orders, a reporter determines a mean order time of 63 minutes. Let µ represent the average number of minutes to fill an order. What is the z-statistic?

Answer 1

Solution:

We are given:

μ=60

σ=15.9

n=40

$\bar{x}=63$

$z=\frac{\bar{x}-\mu}{\frac{\sigma}{\sqrt{n}}}$

         $=\frac{63-60}{\frac{15.9}{\sqrt{40}}}$

         $=\frac{3}{2.5140}$

         $=1.19$

Therefore, the z-statistic is 1.19

Answer 2

Answer:

the first answer is 1.19

the second answer is 1.65