91Ó°ÊÓ

In Exercises 15–18, determine whether the sample is biased. Explain your reasoning. Your school principal randomly selects fi ve students from each grade to complete a survey about classroom participation.

The staff of a student newsletter wants to conduct a survey of the students' favorite television shows. There are 1225 students in the school. Describe a method for selecting a random sample of 250 students to survey.

In a survey, \(8 \%\) of adult Internet users said they participate in sports fantasy leagues online. The margin of error is \(\pm 4 \%\). Describe and correct the error in calculating the sample size. $$ \begin{aligned} \pm 0.08 &=\pm \frac{1}{\sqrt{n}} \\ 0.0064 &=\frac{1}{n} \\ n & \approx 156 \end{aligned} $$

A national collegiate athletic association wants to survey 15 of the 120 head football coaches in a division about a proposed rules change. Describe a method for selecting a random sample of coaches to survey.

Determine whether the inverse of \(f\) is a function. Then find the inverse. \(f(x)=\frac{3}{x+5}\)

Ages: \(24,21,22,26,22,23,25,23,23,24,20,25\)

In a random sample of 2500 consumers, \(61 \%\) prefer Game A over Game B. Describe and correct the error in giving an interval that is likely to contain the exact percent of all consumers who prefer Game A over Game B. Margin of error \(=\frac{1}{\sqrt{n}}=\frac{1}{\sqrt{2500}}=0.02\) It is likely that the exact percent of all consumers who prefer Game A over Game B is between \(60 \%\) and \(62 \%\).

MAKING AN ARGUMENT A random sample of five people at a movie theater from a population of 200 people gave the film 4 out of 4 stars. Your friend concludes that everyone in the movie theater would give the film 4 stars. Is your friend correct? Explain your reasoning.

Your friend states that it is possible to have a margin of error between 0 and 100 percent, not including 0 or 100 percent. Is your friend correct? Explain your reasoning.

In Exercises 21–24, identify the method of data collection the situation describes. The owner of a restaurant asks 20 customers whether they are satisfied with the quality of their meals.