The most commonly used criteria for measuring forecast error is

In a forecasting model, at the end of period $$13,$$ the forecasted value for period $$14$$ is $$75.$$ Actual value in the periods $$14$$ to $$16$$ are constant at $$100$$. if the assumed simple exponential smoothing parameter is $$0.5,$$ then the $$MSE$$ at the end of period $$16$$ is

The cost of providing service in a queuing system increases with

People arrive at a hotel in a Poisson distributed arrival rate of $$8$$ per hour. Service time distribution is closely approximated by the negative exponential. The average service time is $$5$$ minutes. Calculate (a) the mean number in the waiting line; (b) the mean number in the system; (c) the waiting time in the queue; (d) the mean time in the system, and (e) the utilization factor.