A vending machine dispenses hot chocolate or coffee. Service duration is 25 seconds per cup and is constant. Customers arrive at a mean rate of 94 per hour (assume Poisson). Also assume that each customer buys only one cup. Determine the average time customers spend in the system.

Select one: a. 0.0279 hours b. 0.0135 hours c. 0.0056 hours d. 0.0295 hours