A simple random sample of 60 items resulted in a sample mean of 65. The population standard deviation is 14. a. Compute the 95% confidence interval for the population mean (to 1 decimal).

The 95% confidence interval for the population mean is between 61.5 and 68.5.

Step-by-step explanation:

We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of .

So it is z with a pvalue of , so

Now, find M as such

In which is the standard deviation of the population and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 65 - 3.5 = 61.5

The upper end of the interval is the sample mean added to M. So it is 65 + 3.5 = 68.5

The 95% confidence interval for the population mean is between 61.5 and 68.5.