1. ## CDF to PDF

2. Originally Posted by NaeL
For CDF $F(x)$ and PDF $f(x),$ we have the relation...
$\frac{d}{dx}F(x) = f(x)$
Also, you know $\int_a^b f(x) = 1$ where $x$ is defined on $a You can use this fact to find $K.$
For the last part note that $F(x) = P(X\leq x)$ and $F(x)$ is given. Also, $P(a\leq x \leq b) = \int_a^b f(x)dx.$