A survey of 80 randomly selected companies asked them to report the annual income of their presidents. Assuming that incomes are normally distributed with a standard deviation of $30,000, determine the 90% confidence interval estimate of the mean annual income of all company presidents. Interpret the statistical results.

The 90% confidence interval estimate of the mean annual income of all company presidents is ($579,545, $590,580).

Step-by-step explanation:

The information provided is:

The critical value of z for 90% confidence level is, 1.645.

Compute the 90% confidence interval estimate of the mean annual income of all company presidents as follows:

Thus, the 90% confidence interval estimate of the mean annual income of all company presidents is ($579,545, $590,580).

This interval implies that there is 90% probability that the true mean annual income of all company presidents is within this interval.