If a class's scores are normally distributed,with a mean of 70 and a standard deviation of 10,what are the upper and lower limits of the middle 68% of the class?
A)50 and 90
B)40 and 100
C)60 and 80
D)32 and 68

Question

Quizplus · Accepted Answer

The middle 68% of a normally distributed dataset falls within one standard deviation from the mean. Since the mean is 70 and the standard deviation is 10, one standard deviation below the mean is 60 (70-10) and one standard deviation above the mean is 80 (70+10). Therefore, the upper and lower limits of the middle 68% of the class are 60 and 80.

If a Class's Scores Are Normally Distributed,with a Mean of 70