Posted by raja harishchandra on Tuesday, June 11, 2013 at 2:48am.
Consider a 25×25 grid of city streets. Let S be the points of intersection of the streets, and let P be the set of paths from the bottom left corner to the top right corner of which consist of only walking to the right and up. A point s is chosen uniformly at random from S and then a path p is chosen uniformly at random from P. Over all (s,p) pairs, the probability that the point s is contained in the path p can be expressed as a/b where a and b are coprime positive integers. What is the value of a+b?

math  ok, Wednesday, June 12, 2013 at 6:54am
where did you get this question?

math  Anonymous, Thursday, June 13, 2013 at 9:58pm
to ok. if you want to answer this on the site brilliant, you can by making an account but unfortunately, in every account, they have different sets of question basing on the level what you are in. this is such a very easy question.

math  ok, Friday, June 14, 2013 at 6:38am
I found that once you solve a problem you can share links.
I don't want to make accounts.