Question

You want to estimate the mean salary of people in a country, so you take a random sample of 81 people from around the country. The sample had an average salary of 8450.00 dollars with population standard deviation of 500.00 dollars. Calculate the Lower Limit of the 99% confidence interval for the mean salary of the people in the country. 

Reminder: You only need to calculate the Lower Limit of the confidence interval. 

_______ 

Answer 1

Solution :

The lower limit of 99% confidence interval of population mean is given as follows :

o ī – 20.02 0.01 2 (ur.

Where, x̄ is sample mean, σ is population standard deviation, n is sample size and Z_(0.01/2) is critical z-value to construct 99% confidence interval.

We have, x̄ = 8450.00, σ = 500.00 and n = 81

Using Z-table we get, Z_(0.01/2) = 2.576

8450.00 – 2.576 x 500 V81

(8450.00 -143.10

8306.00

The lower limit of 99% confidence interval for the mean salary of the people in the country is 8306.90 dollars.