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What is the difference between descriptive and inferential statistics?

The numbers of text messages sent each day by a random sample of 30 teen cellphone users are shown in the table. Estimate the population mean \(\mu\). Number of Text Messages $$ \begin{array}{|l|l|l|l|l|} \hline 30 & 60 & 59 & 83 & 41 \\ 37 & 66 & 63 & 60 & 92 \\ 53 & 42 & 47 & 32 & 79 \\ 53 & 80 & 41 & 51 & 85 \\ 73 & 71 & 69 & 31 & 69 \\ 57 & 60 & 70 & 91 & 67 \\ \hline \end{array} $$

Describe the difference between an unbiased sample and a biased sample. Give one example of each.

In Exercises 5–8, identify the type of sample described. The owners of a chain of 260 retail stores want to assess employee job satisfaction. Employees from 12 stores near the headquarters are surveyed.

In Exercises 5–8, identify the type of sample described. Each employee in a company writes their name on a card and places it in a hat. The employees whose names are on the first two cards drawn each win a gift card.

A survey asks a random sample of U.S. teenagers how many hours of television they watch each night. The survey reveals that the sample mean is 3 hours per night. How confident are you that the average of all U.S. teenagers is exactly 3 hours per night? Explain your reasoning.

When the President of the United States vetoes a bill, the Congress can override the veto by a two-thirds majority vote in each House. Five news organizations conduct individual random surveys of U.S. Senators. The senators are asked whether they will vote to override the veto. The results are shown in the table. (See Example 2.) $$ \begin{array}{|c|c|c|} \hline \begin{array}{c} \text { Sample } \\ \text { Size } \end{array} & \begin{array}{c} \text { Number of Votes } \\ \text { to Override Veto } \end{array} & \begin{array}{c} \text { Percent of Votes } \\ \text { to Override Veto } \end{array} \\ \hline 7 & 6 & 85.7 \% \\ 22 & 16 & 72.7 \% \\ 28 & 21 & 75 \% \\ 31 & 17 & 54.8 \% \\ 49 & 27 & 55.1 \% \\ \hline \end{array} $$ a. Based on the results of the first two surveys, do you think the Senate will vote to override the veto? Explain. b. Based on the results in the table, do you think the Senate will vote to override the veto? Explain.

In Exercises 5–8, identify the type of sample described. The owner of a community pool wants to ask patrons whether they think the water should be colder. Patrons are divided into four age groups, and a sample is randomly surveyed from each age group.

Your teacher lets the students decide whether to have their test on Friday or Monday. The table shows the results from four surveys of randomly selected students in your grade who are taking the same class. The students are asked whether they want to have the test on Friday. $$ \begin{array}{|c|c|c|} \hline \begin{array}{c} \text { Sample } \\ \text { Size } \end{array} & \begin{array}{c} \text { Number of } \\ \text { "Yes" Responses } \end{array} & \begin{array}{c} \text { Percent of } \\ \text { Votes } \end{array} \\ \hline 10 & 8 & 80 \% \\ 20 & 12 & 60 \% \\ 30 & 16 & 53.3 \% \\ 40 & 18 & 45 \% \\ \hline \end{array} $$ a. Based on the results of the first two surveys, do you think the test will be on Friday? Explain. b. Based on the results in the table, do you think the test will be on Friday? Explain.

A national polling company claims that \(54 \%\) of U.S. adults are married. You survey a random sample of 50 adults. (See Example 3.) a. What can you conclude about the accuracy of the claim that the population proportion is \(0.54\) when 31 adults in your survey are married? b. What can you conclude about the accuracy of the claim that the population proportion is \(0.54\) when 19 adults in your survey are married? c. Assume that the true population proportion is 0.54. Estimate the variation among sample proportions for samples of size 50.