grandes-ecoles 2021 Q1a

grandes-ecoles · France · x-ens-maths2__mp Probability Definitions Probability Using Set/Event Algebra
Let $s > 1$ be a real number and let $X$ be a random variable taking values in $\mathbb{N}^*$ following the zeta distribution with parameter $s$. If $n \in \mathbb{N}^*$, we denote $\{n \mid X\}$ the event ``$n$ divides $X$'' and $\{n \nmid X\}$ the complementary event.
Calculate $P(n \mid X)$ for $n \in \mathbb{N}^*$.
Let $s > 1$ be a real number and let $X$ be a random variable taking values in $\mathbb{N}^*$ following the zeta distribution with parameter $s$. If $n \in \mathbb{N}^*$, we denote $\{n \mid X\}$ the event ``$n$ divides $X$'' and $\{n \nmid X\}$ the complementary event.

Calculate $P(n \mid X)$ for $n \in \mathbb{N}^*$.