Egg Beaters are egg substitutes with no fat or cholesterol. The Original Egg Beaters are produced to have 5 grams of protein, one less gram than a regular egg.23 To check the protein claim, 18 Egg...

Egg Beaters are egg substitutes with no fat or cholesterol. The Original Egg Beaters are produced to have 5 grams of protein, one less gram than a regular egg.23 To check the protein claim, 18 Egg Beaters were randomly selected and the amount of protein in each was measured. The resulting data are given in the following table.

Is there any evidence to suggest the mean amount of protein in an Egg Beater is less than 5 grams? Assume the distribution of protein is normal and s =0.95. Use a = 0.02.

Residential mailboxes in Des Moines, Iowa, should be installed such that the bottom of the mailbox is 42 inches above the ground. This rule is designed for safety and to accommodate short mail carriers. A random sample of 75 mailboxes in the city was selected. The height of each was carefully measured, and the sample mean was 43.22 inches. Assume s = 7.6 inches and use a = 0.05. Is there any evidence to suggest the true mean height of mailboxes in Des Moines is different from 42 inches?