Poisson distribution is a discrete probability distribution used to model the number of times an event occurs over a specified interval. The parameter/random variable represents the mean number of occurrences over the specified interval. The formula for the Poisson random variable, where λ is the mean number of occurrences in the interval, is given below for calculating the probability of x occurrences:
f(x) = (e^(-λ) * λ^x) / x!
Before the formula can be used, the time intervals must be the same. Since we want to find the probability of a certain number of occurrences over a specified interval, we are given that the mean number of calls per hour is 24 calls. To convert the mean number of calls per hour to the mean number of calls per minute, we must use the following conversion factor:
(mean number of calls per hour) * (hour/60 minutes)
To find the mean number of calls per minute interval, multiply the mean number of calls per minute by the time interval in minutes:
(mean number of calls per minute) * (time interval in minutes)