Convert 36 calls per hour to calls per minute. 36 1 hour = 0.60 0.6 calls per minute hour 60 minutes To find the mean number of calls per 5-minute interval, multiply the mean number of calls per minute by 5. (5 minutes)(mean number of calls per minute) = 5( 0.60 0.6) = 3 3 calls per 5 minutes Thus, for a 5-minute time interval, we have pl = 3 3 and x = 4 Step 2 Now that the values of u = 3 and x = 4 are on the same 5-minute time interval, the formula for the Poisson distribution can be applied. Find the probability of receiving 4 calls in a 5-minute interval of time, rounding the result to four decimal places. f(x) ure" x! 34 (6-3) = II