Two infinite parallel plates are placed at a certain distance apart. An infinite radiation shield is inserted between the plates without touching any of them to reduce heat exchange between the plates. Assume that the emissivities of plates and radiation shield are equal. The ratio of the net heat exchange between the plates with and without the shield is

Demand during lead time with associated probabilities is shown below:

Expected demand during lead time is ___________

The precedence relations and duration (in days) of activities of a project network are given in the table. The total float (in days) of activities $$e$$ and $$f,$$ respectively, are

At a work station, $$5$$ jobs arrive every minute. The mean time spent on each job in the work station is $$1/8$$ minute. The mean steady state number of jobs in the system is __________