Posted by shayan on Thursday, July 18, 2013 at 3:00am.
An ant starts a random walk on the real number line at 0. At each step, the ant moves by +1 or −1 with equal probability. After 6 moves, the probability that the ant is on a positive number can be expressed as a/b, where a and b are positive coprime integers. What is the value of a+b?

mathsssssssssaaaaaaaaaaaaaaaa  Anonymous, Sunday, July 21, 2013 at 3:44pm
3/8 so 3+8=11