Use the Empirical Rule to Describe Data That Are Bell Shaped
-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 430 with a standard deviation of 50 on a standardized test. Assuming a bell-shaped distribution, what percentage of scores exceeded 330 ?
A) approximately $97.5 \%$
B) approximately $95 \%$
C) approximately $2.5 \%$
D) approximately $84 \%$

Question

Quizplus · Accepted Answer

The Empirical Rule states that for a bell-shaped distribution, approximately 95% of the data falls within two standard deviations of the mean. In this case, the mean is 430 and the standard deviation is 50. So, two standard deviations above the mean is 430 + (2 * 50) = 530. Therefore, approximately 95% of the scores fall between 330 and 530.

Use the Empirical Rule to Describe Data That Are Bell 97.5%97.5 \%97.5%

Use the Empirical Rule to Describe Data That Are Bell $97.5 \%$