A man takes a step forward with probability 0.4 and backward with probability 0.6. Find the probability that at the end of 11 steps, he is one step away from the starting point.

Answer

A, B, C, D

Explanation

The man will be one step away from the starting point, if
(i) either he is one step ahead or (ii) one step behind the starting point.
The man will be one step ahead at the ebnd of eleven steps, if he moves six steps forward and five steps backward. The probability of this event is `overset(11)""C_(6)(0.4)^(6)(0.6)^(5)+overset(11)C_(6)(0.6)^(6)(0.4)^(5)=overset(11)""C_(6)(0.24)^(5)`