Question

The supply chain manager at a distribution center is interested in determining a confidence interval for the average time to process an order. A sample of 20 orders is taken and the mean time was found to be 8 minutes with a standard deviation of 2.2 minutes. What is the 90% confidence interval for the population mean?

Select one:

a. 8 + 0.8506

b. 8 + 0.4919

c. 8 + 1.96

d. 8 + 2.2

Answer 1

Solution :

Given that,

t _/2,df = 1.729

At 90% confidence level of is ,

t_/2,df * (s /n)

8 1.729 * (2.2 / 20)

8 0.8506

option a. is correct