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Question

On an average, there are 30 customers in a queue. If the arrival rate of customers into the system is 16 customers per hour and on average 32 customers leave the system per hour, then the average number of customers in the system is

The correct answer is
30.5

Queueing System Analysis: Average Customers Calculation

This solution explains how to calculate the average number of customers in a queueing system using the provided information about the queue length, arrival rate, and departure rate.

Key Formula

The average number of customers in the system (L) is the sum of the average number of customers waiting in the queue (Lq) and the average number of customers currently being served. In many standard queueing models, the average number of customers being served can be represented by the ratio of the arrival rate (λ) to the departure rate (μ) when the system is in a steady state. The formula is:

$L = L_{q} + \frac{\lambda}{\mu}$

Given Information

  • Average customers in the queue, Lq = 30
  • Arrival rate of customers, λ = 16 customers per hour
  • Departure rate of customers, μ = 32 customers per hour

Step-by-Step Calculation

  1. Identify the variables: We have Lq = 30, λ = 16, and μ = 32.
  2. Calculate the average number of customers being served: This is given by λ/μ.

    $\frac{\lambda}{\mu} = \frac{16}{32} = 0.5$

  3. Calculate the average number of customers in the system (L): Add the average number in the queue to the average number being served.

    $L = L_{q} + \frac{\lambda}{\mu} = 30 + 0.5 = 30.5$

Result

The average number of customers in the system is 30.5.

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Important Questions from Queueing Theory

  1. The probability of getting a total of 7 on two dice thrown together is:

  2. If moment generating function of continuous random variable X is \(\frac{λ}{λ-t}\)  t < λ, then E(X 3) equals to:

  3. If moment generating function of discrete random variable X is (q + pe t) n, then E(X 2) equal to

  4. If A and B are mutually exclusive events such that P(A) P(B) > 0, then which option is correct?

  5. Two random variables X and Y are said to be independent if:

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