In a normal distribution of test scores:
A)all the scores fall within ±1 standard deviation of the mean
B)approximately 68% of the scores fall within ±2 standard deviations of the mean
C)approximately 50% of the scores fall within ±1 standard deviation of the mean
D)approximately 68% of the scores fall within ±1 standard deviation of the mean

Question

Quizplus · Accepted Answer

In a normal distribution, approximately 68% of the scores fall within ±1 standard deviation of the mean. This is known as the empirical rule or 68-95-99.7 rule. Option A is incorrect because not all scores fall within ±1 standard deviation of the mean, there will always be some scores that fall outside this range. Option B is incorrect because approximately 95% of the scores fall within ±2 standard deviations of the mean. Option C is also incorrect because approximately 68% of the scores, not 50%, fall within ±1 standard deviation of the mean.

In a Normal Distribution of Test Scores