Customers arrive at the local PharmCal gas station at the rate of 40 per hour. What service rate is necessary to keep the average wait time less than 5 minutes?
(a) ≅ 45 per hour
(b) ≅ 47 per hour
(c) ≅ 49 per hour
(d) ≅ 50 per hour
(e) none of the above