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Additional Algo $16-9$ Queues when Demand and Service Rates Are Variable $-$ One Server

In a queueing system, customers arrive once every $4$ hours $($standard deviation $=7)$ and services take $3$ hours $($standard deviation $=$

$4\mathrm{.}9).$

What is the average number of customers in the system?

Note: Do not round Intermedlate calculations. Round your answer to $3$ decimal places.