Consider the following sample data with mean and standard deviation of 20.5 and 5.4, respectively.

Class .............................. Frequency

Less than 10 ............................. 25

10 up to 20 .............................. 95

20 up to 30 .............................. 65

30 or more ................................ 15

....................................... n = 200

a. Using the goodness-of-fit test for normality, specify the competing hypotheses in order to determine whether or not the data are normally distributed.

b. At the 5% significance level, what is the critical value? What is the decision rule?

c. Calculate the value of the test statistic.

d. What is the conclusion?