If the quality of teaching is similar in a school, the scores on a standardized test will have a standard deviation of 14. 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 156 with a standard deviation of 2.4354. is there evidence that the standard deviation of test scores has decreased at the α=0.01 level? assume the population is normally distributed.