Digital PSAT Math Practice Question 245: Answer and Explanation

Question: 245

The table below gives the results of a survey of a randomly selected sample of 400 fifteen- and sixteen-year-olds. Each respondent selected the method of electronic communication that he or she used the most.

Primary Method of Electronic Communication

The table omitted the value for x in the bottom row. Based on the structure of the table, what should its value be?

• A. 24
• B. 38
• C. 57
• D. 65

Correct Answer: D

Explanation:

(D) Look at the bottom row. There are a total of 400 individuals, and each selected one type of communication that they preferred, so the first four numbers in the bottom row must add up to 400:

195 + x + 70 + 70 = 400. Combine like terms on the left side of the equation.

335 + x = 400. Subtract 335 from both sides to isolate x:

x = 65, answer (D).

Alternatively, you could have added up the first two terms in the email column to obtain x: 20 + 45 = 65.