For each student in a certain class, a teacher adjusted the student’s test score using the formula $$y = 0.8x + 20$$

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For each student in a certain class, a teacher adjusted the student’s test score using the formula $$y = 0.8x + 20$$

by Gmat_mission » Sun Sep 12, 2021 9:15 am

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For each student in a certain class, a teacher adjusted the student’s test score using the formula $$y = 0.8x + 20$$, where $$x$$ is the student’s original test score and y is the student’s adjusted test score. If the standard deviation of the original test scores of the students in the class was 20, what was the standard deviation of the adjusted test scores of the students in the class?

A. 12
B. 16
C. 28
D. 36
E. 40