Question

If the quality of teaching is similar in a school, the scores on a standardized test will have a standard deviation of 29. The superintendent wants to know if there is a disparity in teaching quality, and decides to investigate whether the standard deviation of test scores has changed. She samples 24 random students and finds a mean score of 163 with a standard deviation of 20.7366. Is there evidence that the standard deviation of test scores has decreased at the α=0.005 level? Assume the population is normally distributed.

Step 2  

Determine the critical value(s) of the test statistic. If the test is two-tailed, separate the values with a comma. Round your answer to three decimal places.

Step 3

Determine value of test statistic

Step 4

reject or fail to reject

Step 5

What is conclusion?

Answer 1