In a previous study conducted several years ago, a man owned on average 15 dress shirts. The standard deviation of the population is 3. A researcher wishes to see if that average has changed. He selected a random sample of 45 men and found that the average number of dress shirts that they owned was 13.8. At a = 0.01, is there enough evidence to support the claim that the average has changed? Assume that the variable is normally distributed. Use the P-value method with tables.