grandes-ecoles 2015 QV.E

grandes-ecoles · France · centrale-maths1__psi Probability Definitions Almost Sure Convergence and Measure-Theoretic Probability
Let $(A_n)_{n\in\mathbb{N}}$ be a sequence of events all with probability 1.
Show that $P\left(\bigcup_{n\in\mathbb{N}}\overline{A_n}\right)=0$. What can be deduced for $P\left(\bigcap_{n\in\mathbb{N}}A_n\right)$?
Let $(A_n)_{n\in\mathbb{N}}$ be a sequence of events all with probability 1.

Show that $P\left(\bigcup_{n\in\mathbb{N}}\overline{A_n}\right)=0$. What can be deduced for $P\left(\bigcap_{n\in\mathbb{N}}A_n\right)$?