[Math] CDF with absolute value

probabilityprobability distributionsprobability theory

I am working on a problem that is finding the CDF of a random variable X from a density function that has an absolute value. My question shares some similarity to this one where I imagine to solve it, you need to use some sort of splitting of the integration.

The problem: Find the CDF for the random variable from:

f(x) = $|x|\over10$, on -2$\le$x$\le$4

0, otherwise

What I have done so far:

Fx(x) = $\int_{-\infty}^{-2}$f(x) d(x) = 0

Fx(x) = $\int_{-2}^4$ f(x) d(x) = 1

The CDF is something along the lines of:

Fx(x) = $1\over10$$\int_{a}^0$|x|d(x) + $1\over10$$\int_{0}^{a}$|x|d(x)

Not sure if I am on the right track here

Best Answer

$F(y) = \int_{-\infty}^y f(x) \ dx$

if $y< 0$

$F(y) = \int_{-2}^y \frac {-x}{10} \ dx$

if $y\ge 0$

$F(y) = \int_{-2}^0 \frac {-x}{10} \ dx + \int_0^y \frac {x}{10} \ dx$

Giving you a piece-wise function.

Related Question