The order and degree of differential equation of all tangent lines to the parabola $x^2=4 y$ is respectively.

The probability distribution of a discrete random variable X is

$\mathrm{X}$	0	1	2	3	4
$\mathrm{P(X=}x)$	$\mathrm{2k}$	$\mathrm{k}$	$\mathrm{2k}$	$\mathrm{4k}$	$\mathrm{k}$

If $\mathrm{a}=\mathrm{P}(x<3)$ and $\mathrm{b}=\mathrm{P}(2 \leq \mathrm{X}<4)$, then

If a random variable $X$ has the p.d.f. $f(x)=\left\{\begin{array}{cc}\frac{\mathrm{k}}{x^2+1} & , \text { if } 0< x< \infty \\ 0 & , \text { otherwise }\end{array}\right.$ then c.d.f. of X is

If $y=y(x)$ satisfies $\left(\frac{2+\sin x}{1+y}\right) \frac{\mathrm{d} y}{\mathrm{~d} x}=-\cos x$ such that $y(0)=2$, then $y\left(\frac{\pi}{2}\right)$ is equal to