Chapter 11.1, Problem 24E

Preliminary data analyses and other information suggest that you can reasonably assume that the variables under consideration in Exercises 11.21–11.26 are normally distributed. In each case, use either the critical-value approach or the P-value approach to perform the required hypothesis test.

  11.24 Premade Pizza. Homestyle Pizza of Camp Verde, Arizona, provides baking instructions for its premade pizzas. According to the instructions, the average baking time is 12 to 18 minutes. If the times are normally distributed, the standard deviation of the times should be approximately 1 minute. A random sample of 15 pizzas yielded the following baking times to the nearest tenth of a minute.

  At the 1% significance level, do the data provide sufficient evidence to conclude that the standard deviation of baking times exceeds 1 minute? (Note: The sample standard deviation of the 15 baking limes is 1.54 minutes.)