Conditional Probability for Mean/Expected Values

[shinny]

OK since my last thread utterly failed I'll just remake it. Basically, first thing, is conditional means on the course? And secondly, can someone explain how it works? I don't completely get it... What I came up with is:




And then E(X>k) is solved by integrating k to infinity (or whatever the upper bound of f( x) is) for ?

[pHysiX]

haha buddy, i think u can stop stressing coz it's not on the study design. from the probability i did as part of extra uni maths, i haven't even encountered these myself.

[shinny]

Bloody TSFX. This came up in the exam with the lambert-W function etcetc. Guess it really is ridiculous exam in every way possible <_<

[dekoyl]

Bloody TSFX. This came up in the exam with the lambert-W function etcetc. Guess it really is ridiculous exam in every way possible <_<

Heh cool thanks for the heads up. The TSFX 2006 Exam 2 is on the bottom of my exam list. I heard its ridiculous but I'm interested in how hard it is.
Did you find it hard?

[shinny]

Mmm..majority of it is acceptable but time-wise its quite difficult.

[dcc]

OK since my last thread utterly failed I'll just remake it. Basically, first thing, is conditional means on the course? And secondly, can someone explain how it works? I don't completely get it... What I came up with is:




And then E(X>k) is solved by integrating k to infinity (or whatever the upper bound of f( x) is) for ?

Lets say you had the randomly distributed variable X which follows a PDF function for which has the property .

If you know that , then first of all, find the area under the curve of from to .

It turns out that , so now define a new random variable Y which follows a PDF function with equation:

for . We multiply by the reciprocal of the above area to ensure that the area under the NEW curve is equal to 1.  We can see that .

So in this case, we have .

In general, this process can be summarised as:



It seems latex is down at the moment, hopefully that will be fixed soon.

[shinny]

And do we need to know this? =T

[dekoyl]

And do we need to know this? =T

I believe that this isn't in the course guide so we don't, thankfully.

[dcc]

And do we need to know this? =T

Not at all

[dekoyl]

 

Not at all

But somehow you know this. So props to you, wise sir.