AP Statistics Chapter

The manager of a city recreation center wants to estimate the percent of city residents who favor a proposal to build a new dog park. To gather data, the manager will select a random sample of city residents. Which of the following is the most appropriate interval for the manager to use for such an estimate?

• A two-sample z -interval for a difference between population proportions.

• A one-sample z -interval for a sample proportion.

• A one-sample z -interval for a difference between population proportions.

• A one-sample z -interval for a population proportion.

• A two-sample z -interval for a difference between sample proportions.

To estimate the average cost of flowers for summer weddings in a certain region, a journalist selected a random sample of 15 summer weddings that were held in the state. A graph of the sample data showed an approximately symmetric distribution with no outliers. The sample mean and standard deviation were $734 and $102, respectively. The journalist will create a 95 percent confidence interval to estimate the population mean. Have all conditions for inference been met?

• No, because the graphical display is approximately symmetric it cannot be assumed that the sampling distribution of sample means is approximately normal.

• No, the sample size of 15 is not less than 10 percent of all weddings in the state.

• No, the 15 weddings in the sample were not selected at random.

• Yes, all conditions have been met.

• No, the sample size is not large enough to assume the sampling distribution of sample means is approximately normal.

Researchers studying the sticky droplets found on spider webs will measure the widths of a random sample of droplets. From the sample, the researchers will construct a 95 percent confidence interval to estimate the mean width of all such droplets. Which of the following statements about a 95 percent confidence interval for the mean width is correct?

• The width of the interval will not be affected if the researchers increase or decrease the number of droplets in the sample.

• The interval will be narrower if the researchers increase the level of confidence to 99 percent.

• The interval will be wider if the researchers decrease the level of confidence to 90 percent.

• The interval will be narrower if the researchers increase the sample size of droplets.

• The interval will be wider if the researchers increase the sample size of droplets.

A town council wants to estimate the proportion of residents who are in favor of a proposal to upgrade the computers in the town library. A random sample of 100 residents was selected, and 97 of those selected indicated that they were in favor of the proposal. Is it appropriate to assume that the sampling distribution of the sample proportion is approximately normal?

• No, because the sample is not large enough to satisfy the normality conditions.

• No, because the size of the population is not known.

• Yes, because the sample is large enough to satisfy the normality conditions.

• Yes, because the sample was selected at random.

• Yes, because sampling distributions of proportions are modeled with a normal model.

Sue and Javier are working on a statistics project to estimate the proportion of students at their school who have a pet dog. Sue selects a random sample of 81 students from the 2,400 students at their school, and Javier selects a separate random sample of 64 students. They will both construct a 90 percent confidence interval from their estimates. Consider the situation in which the sample proportion from Sue’s sample is equal to the sample proportion from Javier’s sample. Which of the following statements correctly describes their intervals?

• Javier’s interval will have a greater degree of confidence than Sue’s interval will.

• Sue’s interval will have a greater degree of confidence than Javier’s interval will.

• The width of Sue’s interval will be narrower than the width of Javier’s interval.

• The width of Sue’s interval will be the same as the width of Javier’s interval.

• The width of Sue’s interval will be wider than the width of Javier’s interval.

What is the method of organizing and summarizing data called?

• The method of organizing and summarizing data is called statistics.

• The method of organizing and summarizing data is called algebra.

• The method of organizing and summarizing data is called calculus.

• The method of organizing and summarizing data is called geometry.

What is making generalizations from a sample to a population called?

• Making generalizations from a sample to a population is called statistical inference.

• Sampling error

• Descriptive statistics

• Data mining

What type of variable involves measurements that can be averaged?

• Variable type that can be averaged is a continuous variable.

• Variable type that can be averaged is a categorical variable.

• Variable type that can be averaged is a nominal variable.

• Variable type that can be averaged is an ordinal variable.

What type of numerical data can only be specific values (counting, shoe sizes, etc)?

• Discrete data

• Continuous data

• Qualitative data

• Nominal data

What type of numerical data can be any value (measurements, etc)?

• Continuous

• Discrete

• Categorical

• Ordinal