grandes-ecoles 2020 Q13

grandes-ecoles · France · centrale-maths2__psi Poisson distribution
Each customer draws a raffle ticket winning a prize with probability $p \in ]0,1[$. The number $N$ of tickets distributed follows a Poisson distribution with parameter $\lambda > 0$. $X$ denotes the number of winning tickets drawn during a day, and $X$ follows a Poisson distribution with parameter $\lambda p$. We consider a real $\alpha \in ]0,1[$ and the condition $$\mathbb{P}(X \geqslant 2) \leqslant 1 - \alpha. \tag{II.1}$$ Using Markov's inequality, prove that if $p \leqslant 2 \frac { 1 - \alpha } { \lambda }$, then condition (II.1) is satisfied.
Each customer draws a raffle ticket winning a prize with probability $p \in ]0,1[$. The number $N$ of tickets distributed follows a Poisson distribution with parameter $\lambda > 0$. $X$ denotes the number of winning tickets drawn during a day, and $X$ follows a Poisson distribution with parameter $\lambda p$. We consider a real $\alpha \in ]0,1[$ and the condition
$$\mathbb{P}(X \geqslant 2) \leqslant 1 - \alpha. \tag{II.1}$$
Using Markov's inequality, prove that if $p \leqslant 2 \frac { 1 - \alpha } { \lambda }$, then condition (II.1) is satisfied.