PSAT Math Multiple-Choice Practice Question 660

Correct Answer: C

Explanation:

(C) A random sample is useful if it is truly random and if it is truly representative of the people being studied.

Choice (C) is correct because it polls a randomly selected group and takes into account only registered voters, which is what you would want to sample if you wanted to predict the results of an election.

Choice (A) is incorrect because it polls only people who go to that grocery store and likely excludes voters who shop elsewhere, are too elderly to shop, or don't have money to spend. It also likely samples a significant number of nonregistered voters who won't be counted in the election.

Choice (B) is incorrect because it polls only people in certain geographical locations and therefore likely people of only certain socioeconomic statuses as well.

Choice (D) is incorrect because it polls only those who have access to the Internet and actually take the time to complete the survey.