A study was designed to investigate the effects of two variables - (1)a studentʹs level of mathematical anxiety and (2)teaching method - on a studentʹs 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 420 with a standard deviation of 20
On a standardized test. Assuming a mound-shaped and symmetric distribution, what percentage
Of scores exceeded 380?
A)approximately 84%
B)approximately 100%
C)approximately 97.5%
D)approximately 95%

Question

Quizplus · Accepted Answer

Given a mound-shaped and symmetric distribution (which suggests a normal distribution), the score of 380 is two standard deviations below the mean (420 - 2*20 = 380). In a normal distribution, about 97.5% of the scores lie above the score that is two standard deviations below the mean.

A Study Was Designed to Investigate the Effects of Two