Week 7 Homework Statistics - Angela Henkemeyer Ch 10 Problems 5 7 13 and 17 Ch 12 Problems 13 and 15 5 The average expenditure on Valentines Day was

# Week 7 Homework Statistics - Angela Henkemeyer Ch 10...

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Angela Henkemeyer 03/02/2015 Ch. 10 Problems 5, 7, 13, and 17. Ch. 12 Problems 13 and 15 5. 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 \$135.67, and the average expenditure in a sample of 30 female consumers was \$68.64. Based on past surveys, the standard deviation for male consumers is assumed to be \$35, and the standard deviation for female consumers is assumed to be \$20. a. What is the point estimate of the difference between the population mean expenditure for males and the population mean expenditure for females? a) The point estimate is \$135.67 - \$68.64 = \$67.03 b. At 99% confidence, what is the margin of error? Using Z-tables, the critical value is Z (0.01/2) = Z (0.005) = ± 2.576 Margin of error, E = Z √1/n1 + 1/n2 = 2.576 √1/40 + 1/30 = 0.62 c. Develop a 99% confidence interval for the difference between the two population means. (X-bar1 – X-bar2) ± E 67.03 ± 0.62 66.41, 67.65 7.

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