Lesson 40-41

The local ranger station tracked and tagged 2,844 adult female black bears in a national park. A random sample of 9 adult female black bears from those tagged had an average body weight of 203 pounds with standard deviation 25 pounds. Which of the following is a point estimate for the population mean weight of all female black bears that are tagged?

• 9

• 25

• 203

• 2388

Tags

CCSS.HSS.IC.B.4

For a certain brand of canned corn, the company claims that the mean weight of the contents of the cans is 15.25 ounces. A random sample of 36 cans were selected. The sample was found to have mean 15.18 ounces and standard deviation 0.12 ounce. A hypothesis test will be conducted to investigate whether there is evidence to support the belief that the mean is less than 15.25 ounces. Which of the following is the correct test statistic?

A random sample of 10 employees of a company was selected to estimate the mean one-way commute time for all employees at the company. The mean and standard deviation of the sample were 38 minutes and 6 minutes, respectively. Assuming all conditions for inference are met, which of the following is the margin of error, in minutes, for a 95 percent confidence interval for the population mean one-way commute time?

Tags

CCSS.HSS.IC.B.4

To test the effectiveness of an exercise program in reducing high blood pressure, 15 participants had their blood pressures recorded before beginning the program and again after completing the program. The difference (after minus before) in blood pressure was recorded for each participant, and the sample mean difference was calculated. A hypothesis test will be conducted to investigate whether there is convincing statistical evidence for a reduction in blood pressure for all who complete the program. Write the null and alternative hypothesis.

To assess the effectiveness of a kindergarten-readiness program, 15 children from a random sample were each given a diagnostic assessment before beginning the program and a follow-up assessment after completing the program. For each child, the difference in the score points between the two assessments was calculated and used to create the 95 percent confidence interval (20.1, 23.9) . Assuming all conditions for inference are met, which of the following is a correct interpretation of the interval?

• For all children in the program, 95 percent of the children will have a mean difference in scores of between 20.1 points and 23.9 points.

• There is a 0.95 probability that the mean difference in scores for all children in the sample is between 20.1 points and 23.9 points.

• There is a 0.95 probability that the mean difference in scores for the children in the program is between 20.1 points and 23.9 points.

• We are 95 percent confident that the mean difference in scores for all children in the program is between 20.1 points and 23.9 points.

• We are 95 percent confident that the mean difference in scores for the children in the sample is between 20.1 points and 23.9 points.

Tags

CCSS.HSS.IC.B.4

• The claim is not plausible because 3 head movements per minute is contained within the interval

• The claim is not plausible because 3 head movements per minute is not contained within the interval.

• The claim is not plausible because 95 percent of 3 is greater than the sample mean of 2.7.

• The claim is plausible because 3 head movements per minute is not contained within the interval

• The claim is plausible because 3 head movements per minute is contained within the interval.

Tags

CCSS.HSS.IC.B.4

A recent study reported the BMI mean body mass index for adults in the United States was 26.8. A researcher believes the mean BMI of marathon runners is less than 26.8. A random sample of 35 marathon runners had a mean BMI of 22.7 with a standard deviation of 3.1. The researcher will conduct a one-sample t-test for a population mean. Have the conditions for inference been met?

• Yes, all conditions have been met.

• No, because the sample was not selected using a random method.

• No, because marathon runners are not a representative sample of all adults in the United States

• No, because the shape of the distribution of the sample is not known.

• No, because the sample size is not large enough to assume normality of the sampling distribution of the sample mean

A university researcher wants to estimate the mean number of novels that seniors read during their time in college. An exit survey was conducted with a random sample of 9 seniors. The sample mean was 7 novels with standard deviation 2.29 novels. Assuming that all conditions for conducting inference have been met, which of the following is a 95 percent confidence interval for the population mean number of novels read by all seniors?

Tags

CCSS.HSS.IC.B.4

The distribution of mass for United States pennies minted since 1982 is approximately normal with mean 2.5 grams. A random sample of 10 pennies minted since 1982 was selected. The sample had a mean mass of 2.47 grams and a standard deviation of 0.04 gram. The test statistic for the population mean has which of the following distributions?

• A normal distribution with mean 0 and standard deviation 1

• A normal distribution with mean 2.5 and standard deviation 0.04

• A normal distribution with mean 2.47 and standard deviation 0.04

• A t-distribution with 9 degrees of freedom

• A t-distribution with 10 degrees of freedom