Question

If the quality of teaching is similar in a school, the scores on a standardized test will have a standard deviation of 11. 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 21 random students and finds a mean score of 176 with a standard deviation of 5.0654. Is there evidence that the standard deviation of test scores has decreased at the α=0.025 level? Assume the population is normally distributed.

Step 2 of 5 : 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 of 5:Determine the value of the test statistic. Round your answer to three decimal places.

Step 4 of 5: Make the decision. (reject or not reject null)

Step 5 of 5: What is the conclusion? (sufficient or insufficient info)

Answer 1