@neel19
Better keep it simple.
There are only two cases when the pivot element gets placed in the worst possible location in the first round of partitioning. i.e. If pivot is at first or at last location of an array.
In that case, T(n) = T(1) + T(n-1) + c.n, and time complexity will be: O (N^2).
So, Probability = Favorable outcome / Total outcome = 2/25.
Feel free to ping if you’ve any doubt :)