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

Answer 1

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