Given the information in Exercise 11.11, and using the 0.05 level of significance in comparing the sample standard deviations, were we justified in assuming that the population standard deviations were equal? Would your conclusion change if the standard deviation for the FoodFarm jars had been 3.0 grams?
In exercise 11.11
A nutritionist has noticed a FoodFarm ad stating the company’s peanut butter contains less fat than that produced by a major competitor. She purchases 11 8-ounce jars of each brand and measures the fat content of each. The 11 FoodFarm jars had an average of 31.3 grams of fat, with a standard deviation of 2.1 grams. The 11 jars from the other company had an average of 33.2 grams of fat, with a standard deviation of 1.8 grams. Assuming normal populations with equal standard deviations, use the 0.05 level of significance in examining whether FoodFarm’s ad claim could be valid.