AP Stats Unit 3 MC Practice

An AP Statistics class starts a project to estimate the average number of hours a student at their high school sleeps per night. Their high school has 1200 students, and they take a sample of the first 120 students that arrive at school on a particular day. They ask each of the 120 students how many hours of sleep they got the night before and then calculate an average. Which of the following statements is an accurate description of the elements of this survey?

• Population: the 120 students surveyed. Parameter of interest: the average number of hours a student at this high school sleeps per night.

• Sample: the 1200 students of the school. Population: all high school students in the United States. Statistic: the average number of hours a student at this high school sleeps per night.

• Sample: the 120 students surveyed. Population: the 1200 students at the high school. Parameter of interest: the average number of hours a student at this high school sleeps per night.

• Sample: the 120 students surveyed. Population: the 1200 students at the high school. Statistic: The average number of hours a student at this high school sleeps per night.

• This is not a survey because a convenience sample was used.

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CCSS.HSS.IC.B.3

At a high school, the cafeteria staff provides optional comment cards to students eating in the cafeteria. Students who wish to make a comment can obtain and fill out a comment card and return it to a drop box in the front office. At the end of the semester, the staff analyzes the responses and finds that 72% of the students who filled out a comment card recommend major changes to the food selection. What conclusions can the cafeteria staff draw from these responses?

• Since all of the students had an opportunity to respond, this is evidence that a majority of all the students supports major changes.

• The cafeteria staff should not use the results to draw any conclusions since some students may not have filled out a comment card, which is nonresponse.

• If the students recorded their grade level with their response, the staff could make the original sample a stratified sample and use the responses to learn what proportion of each grade recommends major changes to food selection.

• The responses were from a voluntary response sample, so the cafeteria staff should not use the results to draw any conclusions.

• The opportunity to fill out comment cards should be offered to students at all high schools in the school district to get a larger sample size, which will make the results more reliable.

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CCSS.7.SP.A.1

CCSS.HSS.IC.A.1

The Career Placement department at a university wants to administer a survey to determine student awareness of the resources offered. The department expects that student awareness of the Career Placement resources will vary significantly depending on how many years a student has attended the university, so they plan to randomly select 30 freshmen, 30 sophomore, 30 juniors, and 30 seniors. This type of sample can be best described as a

• simple random sample.

• systematic sample.

• stratified sample.

• cluster sample.

• block sample.

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CCSS.HSS.IC.B.3

Major League Baseball (MLB) has recently been evaluating the timing of various events during games in an effort to improve the pace of a game. MLB wants to know how long a mound visit, defined as when a coach pauses the game to visit the pitcher on the mound, takes on average. MLB randomly selects 100 games over the course of a season, and records the length, in seconds, of every mound visit that occurs in that game. This sample of mound visits can be best described as a

• simple random sample.

• systematic sample.

• stratified sample.

• cluster sample.

• block sample.

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CCSS.HSS.IC.B.3

Twenty volunteers with high cholesterol were selected for a trial to determine whether a new diet reduces cholesterol. The volunteers were given a low-carb, low-calorie diet. After 8 weeks of the diet, the average cholesterol of the volunteers dropped a significant amount. This study is an example of

• A controlled experiment.

• An uncontrolled experiment.

• A double blind experiment.

• A blocked design experiment.

• An observational study.

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CCSS.HSS.IC.B.3

The Department of Natural Resources (DNR) is planning a study to determine whether breakwaters help decrease erosion at a large lake. They divide the shoreline into 100-foot plots, installing some with breakwaters and some without. However, the east and west shorelines of this lake receive very different wave patterns due to the wind. The DNR suspects this will affect the responses to the breakwaters. Because of this, the DNR plans to treat each shoreline as a different group. This study is an example of

• An uncontrolled experiment.

• A blocked design experiment.

• A matched pairs experiment.

• A stratified random sample.

• A randomized observational study.

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CCSS.HSS.IC.B.3

Forty adult males volunteered to participate in an experiment. Half of them are randomly assigned to take a caffeine supplement before working out, and the other half are assigned to take a placebo before completing the same workout. During the workout, heart rate monitors will be used to measure each participant’s heart rate. The study found that those who took a caffeine supplement had significantly higher average pulse rates during the workout. What conclusion can be drawn from the study?

• Two experimental groups of 20 each is too small to conclude that the results are significant.

• Those that took the caffeine supplement had a higher average heart rate during the workout, but it would not be correct to conclude that caffeine caused this to occur.

• The caffeine supplements caused the heart rates to increase due to the placebo effect.

• Caffeine supplements will, on average, raise the heart rates of all adult males during a workout similar to the one performed in the experiment.

• Caffeine supplements will, on average, raise the heart rates of adult males similar to those in this study during a workout similar to the one performed in the experiment.

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CCSS.HSS.IC.B.3

Diverticulitis is a common intestinal ailment. To test a new medication, a hospital takes 50 volunteers who have a moderate case of the disease. The volunteers are randomly assigned to two treatment groups, one receiving the old medication and one receiving the new medication. The pills are distributed in unmarked pill form so that the patients and medical professionals do not know which medication the patient is taking. Which of the following statements is/are true? Select ALL that apply.

• If the results show that the new medication is significantly more effective than the old medication, we can conclude that the new medication will be more effective for all people that have a moderate case of the disease.

• The group receiving the old medication serves as a control group.

• This is an example of a double-blind experiment.

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CCSS.HSS.IC.B.3

A study is conducted to determine if the blue light from a tablet device will affect the fall asleep time of people in various age groups differently. Volunteers for the study are grouped by age: 18-30, 31-50, and 50+. Half of each group is assigned a standard tablet, the other half is assigned a tablet with reduced blue light. People in each group are asked to use the tablet for 10 minutes before bed and their fall asleep time is recorded. Which of the following is correct?

• Blocks: the three age groups. Treatments: using the standard tablet or the reduced blue light tablet before bed. Response variable: How the eyes react to blue light.

• Blocks: the three age groups. Treatments: measuring how long it takes to fall asleep. Response variable: The hours of sleep recorded.

• Strata: the three age groups. Treatments: using the standard tablet or the reduced blue light tablet before bed. Response variable: How the eyes react to blue light.

• Blocks: the three age groups. Treatments: using the standard tablet or the reduced blue light tablet before bed. Response variable: Time it takes to fall asleep.

• Blocks: the group receiving the standard tablet and the group receiving the reduced blue light tablet. Treatments: using the standard tablet or the reduced blue light tablet before bed. Response variable: Time it takes to fall asleep.

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CCSS.HSS.IC.B.3

A city planner is investigating traffic congestion at a certain intersection. To collect data, a camera will record the number of cars that pass through the intersection at different hours of the day and on different days of the week. Which of the following best describes the type of investigation being conducted by the city planner?

• The investigation is an experiment because the cars go through the intersection at random.

• The investigation is an experiment because the hours and the days are the treatments and the cars are the units.

• The investigation is an observational study because treatments are not imposed.

• The investigation is an observational study because only a sample of cars can go through the intersection on any given day.

• The investigation is a sample survey because the cars that are recorded will inform the city planner about the population of cars on city roads.

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CCSS.HSS.IC.B.3