A data set is found to approximate a normal curve and has a mean of 72.5 and a standard deviation of 10.8.In which range of numbers will 99% of the scores fall?
A) 35.8 - 112.6
B) 44.6 - 100.4
C) 51.3 - 93.7
D) 61.7 - 83.3

Question

Quizplus · Accepted Answer

In a normal curve,99% of the scores fall within 2.58 standard deviations of the mean,or 27.87 in each direction.72.5 - 27.87 = 44.6; 72.5 + 27.87 = 100.4.These numbers have a greater range than 2.58 standard deviations of the mean,so would include more than 99% of the scores.95% of the scores will fall between 2 standard deviations of the mean,or 21.17 each direction,making this range 51.3 - 93.7.68% of scores will fall within 1 standard deviation,with a range of 61.7 - 83.3.

A Data Set Is Found to Approximate a Normal Curve