Proportions or Means Inference

A random sample of 49 medical doctors in LA showed that they worked an average of 53.1 hours/week with a standard deviation of 7.2 hours/week. If the California average is 60 hours/week, does this give evidence that the LA doctors work significantly less than the rest of California?

• One-Sample T Test for a Mean

• two-Sample T Test for a Mean

• Two -Sample Z Test for a Proportion

• One-Sample Z Test for a Proportion

USA Today reported that in 1992, 39% of all elementary school children claimed that when they grow up they want to do something to help other people. However, in 1995, 128 of a random sample of 317 of these same children claimed that when they grow up they want to do something to help other people. Does this information indicate that there has been an attitude change either way?

• One-Sample Z Test for a Proportion
• Two-Sample Z Test for the Difference in Proportions
• One-Sample T Test for a Mean
• Two-Sample T Test for the Difference in Means

The manager of a sporting goods store offered a bonus commission to his salespeople when they sold moregoods. A new manager dropped the bonus system. For a random sample of six sales people, the weeklysales (in thousands of dollars) are shown in the following table with and without the bonus system

Salesperson 1 2 3 4 5 6

with bonus 2.9 3.0 5.8 4.4 5.3 5.6

w/o bonus 2.8 2.5 5.9 3.5 4.6 4.6

• Matched-Pairs T Test for a Mean

• One-Sample T Test for a Mean

• Two-Sample T Test for the Difference in Means

The following is based on information taken from Winter Wind Studies in Rocky Mountain National Park, by Glidden. At five weather stations on Trail Ridge Road in Rocky Mountain National Park, the peak wind gusts (mi/hr) in January and April are recorded below:

Weather station 1 2 3 4 5

January 139 122 126 64 78

April 104 113 100 88 61

Does this information indicate that the peak wind gusts are higher in January than April?

• Two-Sample T Test for the Difference in

• Matched-Pairs T Test for a Mean

• One-Sample T Test for a Mean

In 1975, a random sample of 1484 adult U.S. citizens was surveyed, and 193 strongly agreed with the statement, "People should take care of themselves". Then, in 1991, a survey of 1013 adult U.S. citizens showed that only 61 strongly agreed with the statement. Does this indicate that the proportion of U.S.adults who strongly agree with the given statement has dropped?

• Two-Sample Z Test for the Difference in Proportions
• Two-Sample T Test for the Difference in Means
• Matched Pairs T Test for a Mean
• One-Sample T Test for a Mean

To compare 2 dog-training programs, an obedience school trained 43 dogs using Program A and 41 dogs using Program B. For Program A, the average number of training hours required was 24.8 with a standard deviation of 3.1 hours. For Program B, the mean was 22.9 hours with a standard deviation of 3.3 hours. Is there a significant difference between the two programs?

• One-Sample Z Test for a Proportion

• One-Sample Z Test for a Mean

• Two-Sample T Test for the Difference in Means

• Two-Sample Z Test for the Difference in Proportions

Dannon is supposed to put 29.6 grams of fruit in their fruit-flavored yogurt. To see if enough fruit is being placed in cups of fruit-flavored yogurt, a quality inspector measured the amount in 27 containers.She found an average of 28.9 grams of fruit and standard deviation of 2.8 grams. Does this show that there is probably enough yogurt in the cups?

• One-Sample T Test for a Mean
• One-Sample Z Test for a Proportion
• Matched-Pairs T Test for a Mean
• Chi-Square Goodness of Fit Test

When creating a confidence interval for the difference of 2 proportions, we pool the samples when finding standard error

• True
• False

A random sample of 44 individuals with a B.S. degree in accounting who had started with a “Big Eight” accounting firm and subsequently changed jobs resulted in a mean time to change of 35.02 months and a standard deviation of 18.94 months. At the 0.05 level of significance, is there sufficient evidence to support the claim that true mean time to change exceeds 24 months.

• 1 Sample z Test
• 1 Sample t Test
• 1 Proportion z Test
• x-sq Test

A test question is considered good if it discriminates between unprepared and prepared students. The first question on a test was answered correctly by 23 of 50 unprepared students and by 45 of 80 prepared students. At the 0.05 significance level, test the claim that the proportion of unprepared students who answer the question correctly is less than the proportion of prepared students who answer it correctly.

• 2 Proportion z Test
• 2 Sample z Test
• 1 Proporiton z Test
• 1 Sample z Test