USA Today reports that the average expenditure on Valentine's Day was expected to be $100.89. Do male and female consumers differ in the amounts they spend? The average expenditure in a sample survey of 40 male consumers was $137.27, and the average expenditure in a sample survey of 30 female consumers was $62.65.
Based on past surveys, the standard deviation for male consumers is assumed to be $33, and the standard deviation for female consumers is assumed to be $18. The * 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?
b. At 99% confidence, what is the margin of error?
c. Develop a 99% confidence interval for the difference between the two population means.
