Question

To estimate the average salary among people in a certain district, a marketing team obtains a simple random sample of 100 people from that district. The team sets up the following approximate 90% confidence interval, using a normal estimate, for the unknown average salary (in dollars annually) of the district:

[41500,49750]

__________ Approximately 90% of the people in the district have a salary in the interval
__________ The procedure used to construct the interval works approximately 90% of the time.
_________For the normal estimate of 90% confidence to apply, the salary distribution in the population must be approximately normal.

Answer 1

The interpretation is that we are 90% sure that the true average salary of the district is in this interval.

Explanation:

x% confidence interval:

A confidence interval is built from a sample, has bounds a and b, and has a confidence level of x%. It means that we are x% confident that the population mean is between a and b.

In this question:

The 90% confidence interval for the average salary of the district is [41500,49750].

This means that we are 90% sure that the true average salary of the district is in this interval.