A program to decrease littering was carried out in four cities in California’s Central Valley starting in August 2009. The amount of litter in the streets (average pounds of litter collected per block per day) was measured during the July before the program was started and then the next July, after the program had been in effect for a year. The results were as follows:

Using the .01 level of significance, was there a significant decrease in the amount of litter?

(a) Use the five steps of hypothesis testing.

(b) Sketch the distributions involved.

(c) Explain your answer to someone who understands mean, standard deviation, and variance but knows nothing else about statistics.

City July 2009 July 2010 Fresno 9 2 Merced 10 4 Bakersfield 8 9 Stockton 9 1