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. The number of intervals or categories used to test the hypothesis for this problem is
A) 4.
B) 5.
C) 6.
D) 10.

Question

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.  ​ The number of intervals or categories used to test the hypothesis for this problem is
A) 4. 
B) 5. 
C) 6. 
D) 10.

Quizplus · Accepted Answer

One common rule of thumb for selecting the number of intervals or categories for a normality test is to use the square root of the sample size. In this case, the sample size is 30, so the square root is approximately 5.5. Since it's best to use an even number of intervals for symmetry, we round up to 6 intervals. Therefore, the answer is C.

You Want to Test Whether or Not the Following Sample