Probability of Poisson event occuring at least 3 times in given interval At a parking garage, automobiles enter at a rate of $1$ car every $2$ minutes. 
I need to find the probability that the number of automobiles entering the garage during any $2$ minute period exceeds $3$. 

I know $\Pr(x \gt 3)=  1-\Pr(x\le 3)$.

So, $1-\left(e^{-1} + e^{-1} + \frac{1}{2} e^{-1} + \frac{1}{6} e^{-1}\right) \dots$.
About the statement

The Probability that the event exceeds 3 is not the same that the event happen at least 3 times.

The Probability that the event exceeds 3 is the same as the probability that the event happen at least 4 times.

Then we can perform

P(x>3) = 1 - P(x&lt;=3)

Best Regards
About the statement

The Probability that the event exceeds 3 is not the same that the event happen at least 3 times.

The Probability that the event exceeds 3 is the same as the probability that the event happen at least 4 times.

Then we can perform

P(x>3) = 1 - P(x&lt;=3)

Best Regards