# Probability of events having to deal with a string permutation question

I am studying for a discrete math exam tomorrow and this is one of the review questions. I am having trouble answering the question as of now. If you could provide guidance on how to solve one or more of the following parts of the question, I would be really appreciative!! Let me know if you need any other information!

Assume that a string of length 9 is a random permutation of letters {a, b, c, d, e, f, g, h, i}.

(a) What is the probability of event A: letter g comes before a ?

(b) What is the probability of event B: letter g comes after b and d ?

(c) What is the probability of event C: letters e and f are before b and d ?

(d) Choose an arbitrary pair of events from {A, B, C} above and determine if these two are independent or not.

• For a, there are only two orders of $g$ and $a$. You can just erase all the other letters because you don't care about them. What is the chance $g$ is before $a$? – Ross Millikan Apr 24 at 3:31
• That is correct. Another way to think about it is to choose the last one, which is $g\ 1/3$ of the time. – Ross Millikan Apr 24 at 3:37