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 260 with a standard deviation of 30 on a standardized test. Assuming a mound-shaped and symmetric distribution, what percentage of scores exceeded 200?
A) approximately 97.5%
B) approximately 95%
C) approximately 100%
D) approximately 84%

Question

Quizplus · Accepted Answer

The mean is 260 and the standard deviation is 30. Using the empirical rule, approximately 95% of the scores will fall within 2 standard deviations of the mean, which is 260 +/- 60, or between 200 and 320. Therefore, approximately 95% of the scores exceeded 200.

A Study Was Designed to Investigate the Effects of Two