Lisa Mendes and Brad Lee work in the sales department of an AT&T Wireless Store. Lisa has been signing in an average of 46 new cell phone customers every month with a standard deviation of 23, while Brad signs in an average of 56 new customers with a standard deviation of 15. The store manager offers both Lisa and Brad a $90 incentive bonus if they can sign in more than 90 new customers in a month. Assume a normal distribution to answer the following questions. Use Table 1.
a. What is the probability that Lisa will earn the $90 incentive bonus? (Round "z" value to 2 decimal places and final answer to 4 decimal places.)
b. What is the probability that Brad will earn the $90 incentive bonus? (Round "z" value to 2 decimal places and final answer to 4 decimal places.)