The scores achieved by students in America make the news often, and all kinds of conclusions are drawn based on these scores. The ACT Assessment is designed to assess high school students’

general educational development and their ability to complete college-level work. The following table shows the mean and standard deviation for the scores of all high school graduates in 2001 and in 2004 on the four ACT tests and their composite.

Science English Mathematics Reading Reasoning Composite 2001 Mean 20.5 20.7 21.3 21.0 21.0 Std. Dev. 5.6 5.0 6.0 4.6 4.7 2004 Mean 20.4 20.7 21.3 20.9 20.9 Std. Dev. 5.9 5.0 6.0 4.6 4.8 Source: American College Testing Based on the information in the table:

a. Discuss how the five distributions are similar and different from each other with regard to central value and spread.

b. Discuss any shift in the scores between 2001 and 2004. Include in your answer specifics about how each test distribution has, or has not, changed according to central value and spread.