Hi all.

This is my first forum post, so please forgive me if I have done something wrong.

Now for my problem:

A stochastic variable $\displaystyle X$ is binomial distributed with number of trials $\displaystyle n = 18$ and success probability in each trial $\displaystyle p = 0.4$.

Calculate the probability that $\displaystyle X$ is less than $\displaystyle 11$ when given the fact that $\displaystyle X$ is greather than or equal to $\displaystyle 7$.

My suggestion:

$\displaystyle P(7 \leq X < 11) = P(X > 11) - P(X \geq 7) = P(X \geq 11) - P(X \geq 7) \simeq 0.4163$