The usa today reports that the average expenditure on valentine's day is $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 $135.67, and the average expenditure in a sample survey of 31 female consumers was $68.64. based on past surveys, the standard deviation for male consumers is assumed to be $39, and the standard deviation for female consumers is assumed to be $20.

1. 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)?

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

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