Question

The records of a random sample of 25 Amazon employees in a large city showed that the average years these employees had worked for the Amazon was ?̅= 4 years. Assume that we know that the population distribution of years Amazon employees have spent with the company is approximately Normal, with standard deviation ? = 1.3 years. Assume all conditions have been met. Construct and interpret a 99% confidence interval for the true mean years the population of Amazon employees have spent with the company.

Give the Calculations and interpret:

Answer 1

Solution

Given that,

= 4

=1.3

n = 25

At 99% confidence level the z is ,

= 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

Z/2 = Z0.005 = 2.576

Margin of error = E = Z/2* (/n)

= 2.576 * (1.3 / 25 )

= 0.67

At 99% confidence interval estimate of the population mean is,

- E < < + E

4 0.67 < < 4 + 0.67

3.33 < < 4.67

(3.33 , 4.67)