If the sample mean of a continuous variable is 120 and the standard deviation is 5, where would 99% of the data fall? (Assume normal distribution)
A) 110.2 - 129.8
B) 107.1 - 132.9
C) 148.4 - 187.6
D) Cannot say.

Question

Quizplus · Accepted Answer

Using the Empirical Rule or 68-95-99.7 Rule, we can estimate that 99% of the data falls within 3 standard deviations of the mean. Therefore, the range would be 120 + (3 * 5) and 120 - (3 * 5) which equals to 135 and 105. The range of values that fall within this range is 107.1 to 132.9. Therefore, the best choice is B.

If the Sample Mean of a Continuous Variable Is 120