The average expenditure on Valentine's Day was expected to be$100.89 (USA Today, February 13, 2006). Do male and femaleconsumers differ in the amounts they spend? The average expenditurein a sample survey of 40 male consumers was $135.67, and theaverage expenditure in a sample survey of 30 female consumers was$68.64. Based on past surveys, the standard deviation for maleconsumers is assumed to be $35, and the standard deviation forfemale consumers is assumed to be $20. The z value is 2.576 .

Round your answers to 2 decimal places.

a. What is the point estimate of thedifference between the population mean expenditure for males andthe population mean expenditure for females?
___________

b. At 99% confidence, what is the marginof error?
___________

c. Develop a 99% confidence interval forthe difference between the two population means.
_____________ to _________________