easy   Probability

You Win?

A release-checked easy problem for training Poisson, Law of Total Probability, Conditional Distributions, Conditional Probability.

Question

You are a winner of a lottery! However, you may not be the only winner. The number of other people who won the lottery is $N \sim \text{Poisson}(\lambda)$, where $\lambda > 0$ is a constant. Given $N = n$, the person who actually receives all the money is randomly selected from the $n+1$ total winners (you and the other $n$ people). Find the probability that you actually receive the money when $\lambda = 1$, rounded to the nearest thousandth.

Practice focus

This Probability problem is tagged Poisson, Law of Total Probability, Conditional Distributions, Conditional Probability. State the random variables and conditioning information explicitly, then check the result against boundary cases before opening hints or a solution.

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