3.
If two random variables have the joint probability density function $f(x, y) = \begin{cases} k(2x + 3y), & 0 \leq x \leq 1, 0 \leq y \leq 1 \\ 0, & \text{otherwise} \end{cases}$, find (i) constant $k$ (ii) conditional probability density function of $X$ (iii) Identify whether $X$ and $Y$ are independent.
$f(x, y) = \begin{cases} k(2x + 3y), & 0 \leq x \leq 1, 0 \leq y \leq 1 \\ 0, & \text{otherwise} \end{cases}$
[5]