Refer to Exercise 6.39. A similar analysis produced these joint probabilities.

Violent Crime Committed No Violent Crime Enrollment This Year Committed Less than 300 .159 .091 300 to 499 .221 .065 500 to 999 .289 .063 1,000 or more .108 .004

(Source: Statistical Abstract of the United States, 2009, Table 237.)

a. What is the probability that a school with an enrollment of less than 300 had at least one violent crime during the year?

b. What is the probability that a school that has at least one violent crime had an enrollment of less than 300?