# Expectancy (mean) of Probability density function composed of delta/rect function

• Oct 26th 2010, 08:27 AM
T12
Expectancy (mean) of Probability density function composed of delta/rect function
Conceptually I can work it out, but I'm not sure how to put it down mathematically. Since the functions are abstracted a bit. Could some one help write out how this should be done?

pdf : 0.5 delta(t) + 1/4 rect ((t-1)/2)

http://transcendent.www.idnet.com/probdensity.jpg
• Oct 26th 2010, 11:46 AM
nerdo
is this unifrom distribution
• Oct 26th 2010, 12:43 PM
T12
Not sure what you're asking, my graph is meant to show that there's a 50% of the random variable X being 0 and a 50% chance of being uniformly distributed between 0 and 2. I'm unsure how to deal with the dirac delta function when calculating the E[X]... Thanks in advance.
• Oct 26th 2010, 06:55 PM
mr fantastic
Quote:

Originally Posted by T12
Conceptually I can work it out, but I'm not sure how to put it down mathematically. Since the functions are abstracted a bit. Could some one help write out how this should be done?

pdf : 0.5 delta(t) + 1/4 rect ((t-1)/2)

http://transcendent.www.idnet.com/probdensity.jpg

$\displaystyle \displaystyle \mu = 0 \cdot \frac{1}{2} + \int_0^2 \frac{t}{4} \, dt$
• Oct 27th 2010, 05:41 AM
T12
thank you, nice and simple. And sorry for wrong section. I put it there in terms of how simple it should be. Rather than whether pre university people have even heard of dirac delta functions.