The average expenditure on Valentine's Day was expected to be $100.89 (USA Today, February 13, 2006). ...

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 46 male consumers was $135.67, and the average expenditure in a sample survey of 39 female consumers was $68.64. Based on past surveys, the standard deviation for male consumers is assumed to be $38, and the standard deviation for female consumers is assumed to be $22.

a.What is the point estimate of the difference between the population mean expenditure for males and the population mean expenditure for females (to 2 decimals)?

b.At 99% confidence, what is the margin of error (to 2 decimals)?

c.Develop a 99% confidence interval for the difference between the two population means (to 2 decimals).