A owes B Rs.50. He agrees to pay B over a number of consecutive days on a Monday, paying single note or Rs.10 or Rs.20 on each day. In how many different ways can A repay B.
Options:
(A) 2
(B) 8
(C) 9
(D) 6
(E) 5 Stream of consciousness:
He can pay by all 10 rupee notes = 1 way
3 Ten rupee + 1 twenty rupee = 4!3!1!4!3!1! = 4 ways
1 Ten rupee + 2 twenty rupee notes = 3!2!1!3!2!1! = 3 ways
Total ways = 1 + 4 + 3 = 8
Thus, the answer is (B).