Many consumers pay careful attention to stated nutritional contents on packaged foods when making purchases. It is therefore important that the information on packages be accurate. A random sample of n 12 frozen dinners of a certain type was selected from production during a particular period, and the calorie content of each one was determined. (This determination entails destroying the product, so a census would certainly not be desirable!) Here are the resulting observations, along with a boxplot and normal probability plot:

255 244 239 242 265 245 259 248 225 226 251 233

a. Is it reasonable to test hypotheses about mean calorie content m by using a t test? Explain why or why not.

b. The stated calorie content is 240. Does the boxplot suggest that true average content differs from the stated value? Explain your reasoning.

c. Carry out a formal test of the hypotheses suggested in Part (b).