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, in what range would approximately 99.7% of the students score?
A) between 230 and 470
B) below 470
C) above 470
D) below 230 and above 470

Question

Quizplus · Accepted Answer

According to the empirical rule (68-95-99.7 rule), approximately 99.7% of data in a normal distribution lies within three standard deviations from the mean. Here, the mean is 350 and the standard deviation is 40. Thus, the range is 350 ± 3(40), which is 230 to 470.

A Study Was Designed to Investigate the Effects of Two