Imagine that you are the manager of an engineering department that processes requests for quotations for new designs. Your past experience indicates that you receive 7 requests per month. What is the probability that you will receive more than 4 requests next month? The average time it takes one of your engineers to process such a request is 30 hours, with a range of 20 to 60. How many engineers should you have to be able to complete at least 90% of the work each month (everyone works 160 hours per month)?