1.

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

Answer»

Since the man is one step away from starting point means that either 

(i) man has taken 6 steps forward aand 5 steps backward 

Or (ii) man has taken 5 steps forward and 6 steps backward. 

Taking movement 1 step forward as success and 1 step backward as failure. 

∴ p = Probability of success = 0.4 and q = probability of failure = 0.6 

∴ required probability = P (X = 6 or X = 5) 

= P (X = 6) + P (X = 5) 

= 11C6 p6 q5 + 11C5 p5q6 

= 11C5 (p6q5 + p5q6) = 11C5 (p + q) (p5 q5

= 11. 10. 9. 8. 7/1. 2. 3. 4. 5 (0.4 + 0.6) (0.4 x 0.6)

= 462 x 1 x (0.24)5 = 0.37 

Hence the required prob. = 0.37 



Discussion

No Comment Found

Related InterviewSolutions