Question

According to a recent report in Namibia Today on 13 February 2006, the average expenditure on Valentine's day was expected to be about N$101. Do male and female consumers differ in the amounts they spend? The average expenditure in a sample survey of 40 male consumers was N$135.67, and the average expenditure in a sample survey of 30 female consumers was N$68.64. Based on past surveys, the standard deviation for male consumers is assumed to be N$35, and the standard deviation for female consumers is assumed to be N$20.

1.1) What is the point estimate of the difference between the population mean expenditure fo males and and the population mean expenditure for females?
1.2) Test a claim which states that males and females differ in the amounts they spend
1.3) Construct and interpret a 99 percent confidence intervals for the difference between the two population means.