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Question
The average number of phone calls per minute into the switchboard of a company between 10.00 am and 2.30 pm is 2.5. Find the probability that during one particular minute there will be exactly 3 calls
Solution
The average number of phone cells per minute into the switchboard of a company is λ = 2.5
x follows poisson distribution with
P(x) = `("e"^(-lambda) lambda^x)/(x!)`
= `((2^(-2.5) (2.5)^x)/(x!))`
P(exactly 3 calls) = P(X = 3)
= `("e^(-2.5) (2.5)^3)/3`
= `((0.08208) xx 15.625)/6`
= 0.2138
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