Question 1180933
The mean/expected value of the Poisson distribution is the parameter, here 5 calls per minute.
no more than two calls is p(0,1,2)
probability of 0 calls is e^-5*5^0/0!=0.0067
1 call is e^-5*5^1/1!=0.0337
2 calls is e^-5*5^2/2!=0.0842
that sum is 0.1246 rounding each step 0.1247 using no rounding until the end (preferred).