Question

Use the standard normal distribution or the​ t-distribution to construct a

99​%

confidence interval for the population mean. Justify your decision. If neither distribution can be​ used, explain why. Interpret the results.

In a recent​ season, the population standard deviation of the yards per carry for all running backs was

1.31.

The yards per carry of 25 randomly selected running backs are shown below. Assume the yards per carry are normally distributed.

1.3	5.8	6.1	5.6	7.3	7.1	4.7	2.8	3.1	1.7	2.7	7.1	5.7
6.6	3.5	4.2	7.4	4.4	5.7	4.6	7.2	7.3	3.2	5.1	4.3

Answer 1

One need to use normal distribution in this case, as population standard deviation is known.