Differences Between Forecast and Actual High Temperatures Data Set 10 in Appendix B lists the actual high temperatures and the three-day forecast high temperatures. One way to investigate the accuracy of those forecast temperatures is to find the differences between the actual and the forecast temperatures. The 31 differences (actual high 2 three-day forecast high) have a mean of 20.419°. Assuming that s 5 3.704°, we get the results shown in the accompanying TI-83 Plus calculator display.

Interpret those results. Does the mean difference appear to be close to 0°, or does there appear to be a significant difference? What do these results suggest about the accuracy of the three-day forecast high temperatures?