Exhibit 12-7
You want to test whether or not the following sample of 30 observations follows a normal distribution. The mean of the sample equals 11.83, and the standard deviation equals 4.53.
-Refer to Exhibit 12-7. The calculated value for the test statistic equals
A)0
B)1.67
C)2

Question

Exhibit 12-7
You want to test whether or not the following sample of 30 observations follows a normal distribution. The mean of the sample equals 11.83, and the standard deviation equals 4.53. 
-Refer to Exhibit 12-7. The calculated value for the test statistic equals
A)0 
B)1.67 
C)2

Quizplus · Accepted Answer

In order to calculate the test statistic for testing normality, we can calculate the standardized skewness (z-skewness) which is calculated as (3(mean-median))/standard deviation. In this case, the calculated z-skewness equals (3(11.83-11.98))/4.53 = -0.33. Based on the table in Exhibit 12-7, the critical value for a sample size of 30 at the alpha level of 0.05 is 2. Since the calculated z-skewness of -0.33 is less than 2, we fail to reject the null hypothesis that the sample follows a normal distribution. Therefore, the calculated value for the test statistic is 0.

Exhibit 12-7 You Want to Test Whether or Not the Following Sample