House prices: Data from the National Association of Realtors indicate that the mean price of a home in Denver, Colorado, in 2012 was 260.7 thousand dollars. A random sample of 80 homes sold in 2013 had a mean price of 291 thousand dollars. Can you conclude that the mean price in 2013 differs from the mean price in 2012? Assume the population standard deviation is o = 138. Use the α= 0.01 level of significance and the P-value method with the TI-84 calculator.