Chapter 9.4, Problem 20BSC

In Exercises 9–20, assume that the paired sample data are simple random samples and that the differences have a distribution that is approximately normal.

20. Forecast and Actual Temperatures The author recorded actual temperatures (°F) along with the temperatures (°F) that were predicted five days earlier. Results are listed below. Construct 2 99% confidence interval estimate of the mean of the population of all “actual/forecast” differences. What does the result suggest about the accuracy of the forecast temperatures?

Date	9/1	9/5	9/12	9/15	9/22	9K23	9/27	9/30
Actual High	80	73	78	73	82	81	74	62
High Forecast Five Days Earlier	80	79	79	78	73	79	70	69