Exam 9: Inferences From Two Samples

Provide an appropriate response. - $\text { The test statistic for testing hypothesis about two variances is } F = \frac { \mathrm { s } _ { 1 } ^ { 2 } } { \mathrm {~s} _ { 2 } ^ { 2 } } \text { where } \mathrm { s } _ { 1 } ^ { 2 } > \mathrm { s } _ { 2 } { } ^ { 2 } \text {. Describe the numeric }$ possibilities for this test statistic. Explain the circumstances under which the conclusion would be either that the variances are equal or that the variances are not equal.

Construct the indicated confidence interval for the difference between population proportions p1 - p2. Assume that the samples are independent and that they have been randomly selected. - $x _ { 1 } = 20 , n _ { 1 } = 43$ and $x _ { 2 } = 28 , n _ { 2 } = 60 ;$ Construct a $90 \%$ confidence interval for the difference between population proportions $\mathrm { P } 1 - \mathrm { P } 2$ .

Construct a confidence interval for µd, the mean of the differences d for the population of paired data. Assume that the population of paired differences is normally distributed. -Ten different families are tested for the number of gallons of water a day they use before and after viewing a conservation video. Construct a 90% confidence interval for the mean of the differences. Before 33 33 38 33 35 35 40 40 40 31 After 34 28 25 28 35 33 31 28 35 33

Provide an appropriate response. -Compare the technique for decision making about populations using the hypothesis test method and the confidence interval method.

Construct a confidence interval for µd, the mean of the differences d for the population of paired data. Assume that the population of paired differences is normally distributed. -Using the sample paired data below, construct a 90% confidence interval for the population mean of all differences x - y. 6.0 4.5 4.8 2.5 6.3 5.7 3.3 4.4 3.2 4.0