The man is one step away from starting point after 11 steps. This can happen in two ways (i) He takes ft steps forward and t> steps backward. (ii) He takes 6 steps forward and ft steps backwards. ∴ Probability of first case=11C2(0.4)5(0.6)6 Probability of second ease =11C2(0.4)6(0.6)5 Hence required probability =11C5(0.4)5(0.6)6+11C6(0.4)6(0.6)5 =11C5(0.4)5(0.6)5(0.6+0.4)5 =11C5(0.24)5=462(0.24)5