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 no phone at all

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(no phone at all) = P(X = 0)

= `("e"^(-2.5) (2.5)^0)/(0!)`

= `"e"^(-2.5)`

= 0.08208