A new thermostat has been engineered for the frozen food cases in large supermarkets. Both the old and new thermostats hold temperatures at an average of 25?F. However, it is hoped that the new thermostat might be more dependable in the sense that it will hold temperatures closer to 25?F. One frozen food case was equipped with the new thermostat, and a random sample of 26 temperature readings gave a sample variance of 4.3. Another similar frozen food case was equipped with the old thermostat, and a random sample of 20 temperature readings gave a sample variance of 12.7. Test the claim that the population variance of the new thermostat temperature readings is smaller than that for the new thermostat. Use a 5% level of significance. How could your test conclusion relate to the question regarding the dependability of the temperature readings? (Let population 1 refer to data from the old thermostat.) (a) What Is the level of significance? 0.05 State the null and alternate hypotheses.

(b) Find the value of the sample F statistic. (Round your answer to two decimal places.) What are the degrees of freedom?

df _N = 19 df _D = 25

a. Ho: 0 > 0; H: 0 = 0 b. H: 0,2 = 023; H: 02 * 02 2 c. Ho: 01 = 0; H: 0 < 0 d. Ho: 010; H: 0 > 0