Help with Expectation Problem Anyone?

[pete2323]

Let X be a random variable representing the number of times you need to roll a 6 sided die to obtain 2 consecutive 6's.


Find the E (x)

[trsspidey]

I might start

1*P[1] + 2*P[2] +3*P[3] + 4*P[4] and so on...

Doesn't look easy but it might be something to look into?

[pete2323]

Do you mean that p (1) = the probability of 1 roll and p (2)= the probability of 2 rolls?

[trsspidey]

Yep that's what I mean. It looks like an arithmetically increasing series... Not sure if that is the easiest way to get the solution however...Where are you pulling this problem from? Actex?

[pete2323]

got it from actuarial cbt exams........ Can you actually write it out for me or no? Its ok if you don't have the time...... appreciate your help.

[pete2323]

I didn't understand there solution that is why I am asking.

[NoMoreExams]

The search features on here and AO are amazing. You should use them, it will help you with a lot of exam questions and for future work projects: http://www.actuarialoutpost.com/actuarial_discussion_forum/showthread.php?t=111709&highlight=consecutive

[pete2323]

Ok great, thank you..... So I should just type the question in the search menu for both?

[NoMoreExams]

Ok great, thank you..... So I should just type the question in the search menu for both?

I would try to think of what words would be useful. For example I think I used "consecutive 6" or something of the sort. It's important to get good at searching. I've had to use google a lot to pull up studies for ad-hoc projects at work to give me a sense of how good my results compared to what others have done.