Explanation
CALCULATIONS:
The man either takes a step forward or a step backward.
So, 0. 4+ 0. 6= 1,
Let's assume a step forward be a success and a step backward be a failure.
Then, the probability of success in one step=p=0.4=52 Again The probability of failure in one step=q=0.6=53 In 11 steps he will be one step away from the starting point if the numbers of successes and failure differ by 1.
So, the number of successes=6 and number of failures =5 or the number of successes =5 and number of
failures=6
So, the required probability=11C6 p6 q5+11C5 p5 q6
amp;=11C6(52)6(53)5+11C5(52)5(53)6amp;=6!(5)!11!(52)5(53)5{52+53}amp;=12011.10.9.8.7.5102535=462×{256}5=462×{0.24}5
