Let X and Y be two jointly continuous random variables with joint pdf
$$f_{X,Y}(x,y) = \begin{cases}
cx^2y & 0 \le y \le x \le 1 \\
0 & \text{otherwise}
\end{cases}$$
a) Find the constant c
b) Find the marginal pdfs $f_X(x)$ and $f_Y(y)$
c) Find $P(Y \le \frac{1}{4} | Y \le \frac{1}{2})$
d) Find $P(Y \le \frac{x}{2})$