:4. In 1971, the National Assessmet of Educational Progress
(NAEP) administered a reading test to a nationwide random sample
of 1600 9-year olds. The average of the scores was 67.2 (out of
100), and the SD of the scores was 14 points.  In 1975 the NAEP
administered the same test to the members of another random
sample of 1600 9-year olds.  This time, the average score was
68.5, with the SD again being 14.  There appears to have been
some improvement.  Or can this be explained as a chance
variation? If you formulate a null and an alternative hypothesis
in terms of a box model, and use the appropriate test statistic
z,  the P-value turns out to be closest to 
 	
 a. 1 in 5 
 	
 b. 1 in 10 
 	
 c. 1 in 200 
 	
 d. 1 in 500 
 	
 e. 1 in 1000