To determine how citizens feel about the city’s proposed plan to build a second library, researchers surveyed 50 library visitors and found that 42 of them supported the plan and 30 of them would even be open to a tax increase to fund it. Which of the following statements must be true?

Central High School has gotten large enough that the district plans to create a second high school. When the district sent ballots to all of its students and teachers to choose a mascot for the new school, 20% of students and 80% of teachers voted. Of those who voted, 30% of the students and 70% of the teachers chose Sharks as the mascot, and 50% of students and 20% of teachers chose Bears as the mascot. Which of the following conclusions can properly be drawn from the data above?

A marine biologist randomly tagged and measured sharks in the Atlantic Ocean to study their characteristics and habits. The sample included 150 hammerhead sharks, of which 60% measured more than 12 feet in length. Which of the following conclusions is best supported by the data?

Of the 80 ninth grade students Johanna surveyed at random at her high school, 27.5% of them stated that they prefer year-round school to their current schooling system. If this survey is representative of the 280 students in the ninth grade class, which of the following is closest to the number of students in the class who prefer year-round school?

The mayor of a city wants to determine whether the city’s citizens would support a small tax increase to expand and renovate the city’s playgrounds. She randomly surveyed 200 parents who live in the city and found that nearly 75% of them would be in favor of the proposal. Which of the following is true of the survey?

For a school project, a student randomly selected hundreds of books from the public library to learn about their characteristics. Among the sample were 200 novels, only 20% of which were 300 pages or longer. Which of the following conclusions is best supported by the data?

A student wants to find out whether mothers in his city support a local initiative to redesign the city’s largest park. He decides to conduct a poll on this question by calling the home phone numbers of all 300 students in his private high school, asking to speak to their mothers, and recording their responses as yes, no, or no preference. Of the calls, 250 were answered and 200 mothers responded “yes,” with 40 saying “no” and 10 saying “no preference.”

Does this survey lead to the conclusion that most mothers in the city support the initiative to redesign the park?

To determine the average number of pets per household in the town of Los Gatos, a researcher surveyed 100 patrons of the town’s most popular pet supply store. Of the 100 people surveyed, the average number of pets per household was 1.8. Which of the following statements must be true?

The marketing department of a chain of pet stores surveyed a random sample of American families about the number of pets they have. Using the sample data, the department estimates that 81% of families have at least one pet in their home. The margin of error for this estimation is 5%. Which of the following conclusions about all American families can most appropriately be drawn from this data?

A cafeteria service company serves lunches at all 20 schools in a particular school district. In its effort to satisfy students, the company seeks to learn how happy students are with the variety of cafeteria lunch offerings they have, but it suspects that happiness may vary school to school. Which of the following survey methods is most appropriate to estimate the percentage of students in the district who are happy with their cafeteria options?