Question

A new probability question from http://saab.org

Answer 1

Why are you always posting saab questions?

Answer 2

First step you would wan to do is integrate over the y value.
This will make it independent of the Y variable and just a simple probability function of x.

Answer 3

Next thing to do is to find the expected value of the age. In this case age is just x. so you would integrate over all of x using xf_X(x)

Answer 4

Rounding up, my answer would be 5.8

Answer 5

@wio, I am the author of http://saab.org

Answer 6

What is the purpose of saab?

Answer 7

Try it and see. It an interactive web site. The purpose for it is to let students practice
problems mainly in math. The problem's parameters are not the same each time they are generated and a complete solution of the problem is given. Problems that are available cover topics in Algebra, Geometry, Trigonometry, Calculus and Actuarial Science. It also has problems to prepare for the MATHCOUNTS competitions.
The best way to know more is to try it.
By the way, you are very good in Math. What is your Math Background. You can pm if you want.

Answer 8

Here is a solution generated by http://saab.org

Answer 9

My math background is that I went to university and got a computer science degree, so I had to take calc/diff eq/discrete math like the other CS people.

Answer 10

Hmmm, marginal density, I was wondering what f_X(x) was called.

Answer 11

Yes, that is the jargon name for it.