Question 1174512
The errors are proportional to time, so would expect the half-minute distribution to be Poisson with lambda=3.
probability of 0 and 1 are 
p(0)=e^(-3)^3^0/0!=0.0498
p(1)=e^(-3)*3^1/1!=0.1494
that sum is 0.1992
the probability of more than 1 is the complement or 0.8008