Exam 7: Data for Decisions

In order to determine the mean weight of bags of chips filled by its packing machines, a company inspects 50 bags per day and weighs them. In this example, the population is:

A poll asked 956 licensed drivers whether they supported a nationwide lowering of the drunk driving limit to 0.08% BAC (blood alcohol content), and 72% said they did. Estimate a 95% confidence interval for actual percentage among all licensed drivers.

A study gathered data on 1000 randomly selected students and showed that students who took Latin in high school had much higher scores on a test of verbal English skills than those who did not take Latin. The study cannot conclude that taking Latin improves verbal English skills because:

If the 95% confidence interval for the population percentage is determined to be from 65% to 74%, then the population percentage is between 65% and 74% with the probability of 95%.

Define a simple random sample.

Random selection of subjects for surveys is used to avoid:

A farmer believes that exposing chickens to classical music will cause them to produce more eggs. Describe how the farmer may design a randomized comparative experiment to test this theory.

A poll asks 312 randomly selected students whether they prefer the new beaver mascot or the old moose mascot. It turns out that the sample proportion $\hat { p }$ for those preferring the moose is 0.54. What is the margin of error for a 95% confidence interval?

To determine the proportion of students at a university who favor the construction of a parking garage, a student senate member surveys students as they leave the student union. This type of sample is a:

The 200 students in a sociology class at Beta University sit in seats numbered 1 through 200. A good method for obtaining a simple random sample of 10 students is which of the following?

In a poll of 2500 residents of a state, it is found that 480 are in favor of naming the grasshopper the state insect. What is the sample proportion for this poll?

Consider the following situation: Doctors question 5000 women who have had breast cancer to determine if there is a genetic factor that increases the likelihood of cancer. Each woman is asked about her family background and incidences of breast or other types of cancer among her relatives. This describes a prospective study.

A biologist draws a sample of 200 fish from a lake to test for mercury levels. She finds that 8% have levels above the limits set as healthy. Describe the population for this study.

Officials at a university conduct a survey to determine the percentage of students who favor the allocation of a percentage of tuition funds toward the construction of a new campus parking garage. One thousand people driving through the administration building parking lot are surveyed, and it is found that 75% of these people favor the garage. What is the population in this study? What is the sample?

A retrospective study may be used to show cause and effect.

The margin of error given for opinion polls reflects:

The Whitman County Fire Department conducted a survey to determine how the 40,000 residents of the county feel about the fire department's ability to meet their needs. A random sample of 690 citizens was selected, and 627 of them said that they feel confident about the fire department's service. The population is:

A polling company conducted a survey of voters to obtain data for a political campaign. They selected 3500 voters randomly from the 168,000 names on the voter registration lists of the county and found that 1372 intended to vote for candidate Doe. The 3500 voters represent:

Medical experiments are frequently double-blind. Explain what this means and why medical experiments are designed this way.

We wish to know what proportion of students at a major university believes too much emphasis is placed on athletics at the school. Explain how we could choose a sample of 500 students to reduce the possibility of bias in the results.