A frequency distribution has a mean of 200 and a standard deviation of 20. The class limits for one class are 220 up to 240. Based on the normal distribution,what is the probability that an observation would be in this class?
A)0.1359
B)0.3413
C)0.4772
D)0.8185

Question

Quizplus · Accepted Answer

The class limits 220 to 240 are 1 and 2 standard deviations above the mean, respectively. Using the empirical rule, approximately 34.13% of data falls between 1 standard deviation above and below the mean, and 13.59% falls between 2 and 3 standard deviations above the mean. Since the class is between 1 and 2 standard deviations above the mean, the probability is 34.13% - 13.59% = 13.59% for the upper half.

A Frequency Distribution Has a Mean of 200 and a Standard