6. A major tertiary care medical center has decided to establish a sales force to call on physicians practicing in the medical center’s three-state region. The marketing director has classified the physicians into the following categories:

Class A: Loyal referrers—329 physicians Class B: Moderate referrers—480 physicians Class C: Potential referrers—620 physicians She also estimates the following call pattern:

Class A: Four calls per year at 30 minutes per call Class B: Three calls per year at 15 minutes per call Class C: Two calls per year at 15 minutes per call The average salesperson works 48 weeks a year, 40 hours a week, and spends 80%

of his or her time selling. Calculate the number of sales representatives needed to service this market.