A 2018 paper by the National Bureau for Economic Research (NBER Working Paper No. 24639) showed that heat exposure inhibits cognitive skill development. Using results from 10 million PSAT exams, researchers showed that without air conditioning, each 1°F increase in school year temperature reduces the amount learned that year by 1 percent. Your school developed a program to reduce the temperature to levels that promote learning as well as to reduce the standard deviation of the temperature to less than 8 degrees Fahrenheit to avoid spikes in temperatures. To investigate the plan’s effectiveness, a random sample of 20 days was selected for 2018. The data are shown in the following table, and can be found in the Excel file temperature.xlsx.

70 74 69 82 77 68 72 78 66 73
71 81 69 74 72 77 70 68 68 73

a. Using α = 0.05, determine if the standard deviation of temperature is below 8 hours in 2014.

b. Determine the p-value using Excel and interpret its meaning.