TABLE 6-4 John Has Two Jobs. for Daytime Work at a Jewelry

Short Answer

TABLE 6-4
John has two jobs. For daytime work at a jewelry store he is paid $200 per month, plus a commission. His monthly commission is normally distributed with mean $600 and standard deviation $40. At night he works as a waiter, for which his monthly income is normally distributed with mean $100 and standard deviation $30. John's income levels from these two sources are independent of each other.
-Referring to Table 6-4, for a given month, what is the probability that John's commission from the jewelry store is less than $640?