Y by
An ant crawls along the grid lines of an infinite quadrille notebook. One grid point is marked red, this is its starting point. Every time the ant reaches a grid point, it continues forward with probability
, left with probability
, and right with probability
. What is the chance that it is after its third turn, but not after its fourth turn that it returns to the red point?
If the answer is
, where
and
are coprime positive integers, then your answer should be
.
The steps of the ant are independent.



If the answer is




The steps of the ant are independent.