Quiz Chapter 12.docx - Question 1 An F statistic is 2 2 points A population parameter The difference between three means A ratio of two variances A

# Quiz Chapter 12.docx - Question 1 An F statistic is 2 2...

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Question 1 2 / 2 points An F statistic is __________. A population parameter The difference between three means A ratio of two variances A ratio of two means Hide Feedback The F statistic is the ratio of two variances. Question 2 2 / 2 points What distribution does the F distribution approach as the sample size increases? Exponential Poisson Normal Binomial Hide Feedback As the degrees of freedom in both the numerator and denominator increase, the F distribution will approach the normal distribution. Question 3 2 / 2 points Which statement is correct about the F distribution? Is the same as the z distribution Is the same as the t distribution Cannot be positive Cannot be negative Hide Feedback A standard deviation or variance cannot be negative. Therefore, the ratio of two variances cannot be negative, so the F statistic cannot be negative. Question 4 2 / 2 points Analysis of variance is used to _____________. Simultaneously compare several population means
Compare population proportions Compute a t test Compare nominal data Hide Feedback We use the ANOVA technique to compare several treatment means to see if they are equal. Question 5 2 / 2 points A large department store examined a sample of the 18 credit card sales and recorded the amounts charged for each of three types of credit cards: MasterCard, Visa, and Discover. Six MasterCard sales, seven Visa, and five Discover sales were recorded. The store used an ANOVA to test if the mean sales for each credit card were equal. What are the degrees of freedom for the F statistic? 6 in the numerator, 15 in the denominator 2 in the numerator, 15 in the denominator 3 in the numerator, 18 in the denominator 18 in the numerator, 3 in the denominator Hide Feedback The numerator or treatment degrees of freedom are k - 1 = 3 - 1 = 2. The degrees of freedom in the denominator or error degrees of freedom are n - k = 18 - 3 = 15. Question 6 2 / 2 points Suppose an automobile manufacturer designed a radically new lightweight engine and wants to recommend the grade of gasoline that will have the best fuel economy. The four grades are regular, economy, premium, and super premium. The test car made three trial runs on the test track using each of the four grades. The miles per gallon were recorded for each grade. At the 0.05 level, what is the critical value of F used to test the hypothesis that the miles per gallon for each fuel are the same? 12.00 2.33 4.07 1.96
Hide Feedback The numerator or treatment degrees of freedom are k - 1 = 4 - 1 = 3. The degrees of freedom in the denominator or error degrees of freedom are n - k = 12 - 4 = 8. Based on the "Critical values of the F distribution at a 5 percent level of significance" table, the critical value of F is 4.07. Question 7 2 / 2 points Suppose a package delivery company purchased 14 trucks at the same time. Five trucks were purchased from manufacturer A, four from manufacturer B, and five from manufacturer C. The cost of maintaining each truck was recorded. The company used ANOVA to test if the mean maintenance costs of the trucks from each manufacturer were equal. To apply the F test, how many degrees of freedom must be in the denominator?

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