A study was designed to investigate the effects of two variables - (1) a student's level of mathematical anxiety and (2) teaching method - on a student's achievement in a mathematics course. Students who had a low level of mathematical anxiety were taught using the traditional expository method. These students obtained a mean score of 350 with a standard deviation of 40 on a standardized test. Assuming a mound-shaped and symmetric distribution, what percentage of scores exceeded 270?
A) approximately 95%
B) approximately 100%
C) approximately 84%
D) approximately 97.5%

Question

Quizplus · Accepted Answer

The z-score for a score of 270 is (270 - 350) / 40 = -2.00. The percentage of scores exceeding 270 is the area under the normal curve to the right of z = -2.00, which is approximately 97.5%.

A Study Was Designed to Investigate the Effects of Two