I am trying to figure out the following problem but I don't understand exactly how to deal with the conditional expectation. If $X$ is a random variable with CDF $F(x)$ then what is $E[ X | X > w]$?
${E(XI(X>w))\over P(X>w)}= {\int_w^{\infty}xf(x)dx\over 1-F(w)}$