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  • question_answer
    Arrivals at a telephone booth are considered to be poisson with an average time of 10 minutes between one arrival and the next. The length of a phone call is assumed to be distributed exponentially with mean of 3 minutes. The probability that a person arriving at the hook will have to wait, is:

    A) 0.043               

    B) 0.300

    C) 0.429               

    D) 0.700

    Correct Answer: D

    Solution :

    \[\rho =\frac{\lambda }{\mu }=\frac{3}{10}=0.3\] Probability of waiting \[=1-\rho =1-0.3=0.7\]


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