1. Home
  2. PSAT Test
  3. Math Multiple-Choice Tests

PSAT Math Multiple-Choice Practice Question 779

Question: 779

The table below gives the results of a survey of a randomly selected sample of 400 individuals who are 15 and 16 years old. Each respondent selected the method of electronic communication that he or she used the most. 
Primary Method of Electronic Communication
TextingE-mailVideo ChattingOtherTotal
15-year-olds
110
20
40
30
200
16-year-olds
85
45
30
40
200
Total
195
x
70
70
400

The city of Springfield has 50,000 residents ages 15 and 16. Given that the sample in the table is representative of Springfield's residents, approximately how many 15- and 16-year-olds in Springfield would use video chatting as their primary method of electronic communication?

Correct Answer: C

Explanation:

(C) Because we are told that the information in the table is representative of the Springfield population, we expect that the fraction of 15- and 16-year-olds in the survey who prefer video chatting will be the fraction of 15- and 16-year-olds in Springfield who prefer video chatting. The fraction in the survey that prefers video chatting is:
= 0.175
Multiplying this decimal by the number of 15- and 16-year-olds in Springfield gives the number of 15- and 16-year-olds in Springfield that we expect to prefer video chatting:
0.175 × 50,000 = 8,750
Choice (C) is correct.
Alternatively, you could have set up a proportion, Let x denote the total number of 15- and 16-year-olds in Springfield who prefer video chatting. Since there are 50,000 15- and 16-year-old residents in Springfield, our proportion is:

By cross multiplying, we get:
3,500,000 = 400x
Dividing both sides by 400 gives:
x = 8,750

More Tests

All content of site and practice tests © 2022 Jack.
Quick View
PSAT Practice Tests
More Information