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 470 with a standard deviation of 20 on a standardized test. Assuming no information concerning the shape of the distribution is known, what percentage of the students scored between 430 and 510?
A) at least 89%
B) at least 75%
C) approximately 68%
D) approximately 95%

Question

Quizplus · Accepted Answer

According to Chebyshev's theorem, at least 75% of data falls within two standard deviations of the mean for any distribution shape. Here, 430 to 510 is two standard deviations from the mean (470 ± 2*20).

A Study Was Designed to Investigate the Effects of Two