The National Norm for Third Graders on a Standardized Test $\overline{X} = 33.1, s_X = 5.2 and n=30$

Short Answer

The national norm for third graders on a standardized test of reading achievement is a score of 27. Mrs. Johnson obtains the mean score on the test for a random sampling of third graders from her school district. The results for Mrs. Johnson's sample are $\overline{X} = 33.1, s_X = 5.2 and n=30$ (a) Construct the 95% confidence interval for her population mean score. (b) Construct the 99% confidence interval for her population mean score. (c) What generalization is illustrated by a comparison of the answers to (a) and (b)?