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Mathematics>Standard Multiple Choice

Read the following SAT test question and then click on a button to select your answer.

Each year from 2007 to 2015, a group of people were selected at random and surveyed about their use of online radio. The survey asked respondents whether or not they listened to online radio in the last month. The scatterplot shown gives the results of the survey, where P represents the percent of respondents who reported listening to online radio and t represents years since 2007. Which of the following equations best models the relationship between t and P?

A.P=0.23t+18
B.P=t+20
C.P=2.3t+20
D.P=4.3t+18

答案和解析

答案：D

解析：

Choice D is correct. Drawing a best fit line on the scatterplot helps to estimate the slope and y-intercept, or in this case, the P-intercept of the line.

According to the line, the P-intercept is about (0,18) and the slope is greater than 4 but less than 6.

Therefore, of the equations given, P=4.3t+18 is the best model of the relationship between t and P.