Take this Exam: PSAT Data — centers, chances, and what a study is allowed to say | Zestly

Question 1

A researcher surveys 500 students at a large university about their favorite study spot. Which of the following is a valid conclusion based on this sample?

Accepted Answer

The survey results describe the preferences of students at this university.

Answer

The survey results apply to all people in the city.

Answer

All college students in the country prefer the library.

Answer

Students at other universities have the same preferences.

Question 2

A company surveys 200 of its 5,000 employees regarding their satisfaction with the new breakroom. Which of the following is a valid conclusion?

Accepted Answer

The results provide an estimate of satisfaction for the company's employees.

Answer

The results prove that all employees are satisfied.

Answer

The results can be used to predict the satisfaction of employees at other companies.

Answer

The results are invalid because they did not survey all 5,000 employees.

Question 3

A polling group asked a sample of eight hundred residents of Calder County how often they use the county buses, and reported that $38$ percent use them weekly, with a margin of error of plus or minus three percentage points. What does that margin of error indicate?

Accepted Answer

That the true figure for the county is likely to lie between thirty-five and forty-one percent

Answer

That the poll would give the same answer three times out of a hundred

Answer

That three percent of the answers given were wrong

Answer

That thirty-eight percent is the figure for the county, give or take three residents

Question 4

An observational study finds that students who use tablets for homework have higher test scores than those who do not. Why can researchers not conclude that tablets cause higher scores?

Answer

The study did not use a margin of error.

Answer

The test scores were not measured accurately.

Answer

The sample size was too small.

Answer

There may be confounding variables like socioeconomic status.

Question 5

A club recorded nine commuting times in minutes: 14, 15, 15, 17, 18, 20, 21, 22 and 96. The last of these came from a member whose train broke down. If that reading is removed, what happens to the mean and to the median?

Answer

Both fall by about the same amount

Answer

The mean falls sharply and the median barely moves

Answer

The median falls sharply and the mean barely moves

Answer

Neither changes, because the reading was at the end of the list

Question 6

A line of best fit through readings of a seedling's height gives $y = 2.5x + 10$, where $x$ is the number of weeks since planting and $y$ is the height in centimeters. What height does the model predict at eight weeks?

Answer

20 centimeters

Answer

28 centimeters

Answer

30 centimeters

Answer

100 centimeters