The average expenditure on Valentine's Day was expected to be $100.89 (USA Today, February 13, 2006). Do male and female consumers differ in the amounts they spend? The average expenditure in a sample survey of 54 male consumers was $137.64, and the average expenditure in a sample survey of 35 female consumers was $60.73. Based or past surveys, the standard deviation for male consumers is assumed to be $32, and the standard deviation for female consumers is assumed to be $10. The z value is 2.576. Round your answers to 2 decimal places a. What is the point estimate of the difference between the population mean expenditure for males and the population mean expenditure for females? 67.03 b. At 99% confidence, what is the margi of error? .054 c. Develop a 99% confidence interval for the difference between the two population means. 66.95 to 67.05