Boxes numbered 1, 2, 3, 4 and 5 are kept in a row and they which are to be filled with either a red or a blue ball, such that no two adjacent boxes can be filled with blue balls. Then, how many different arrangements are possible, given that all balls of a given colour are exactly identical in all respects ?
Pick:
A) 8  B) 10  C) 15  D) 22  E) 25
total number arrangement without any restriction is 2^5=32   nymber of arrangement in which blue balls are adjacent =bb,bb,bb,bb,bbb,bbb,bbb,bbbb,bbbb,bbbbb=10   hence required number= 32-10= 
<gadget id="calculator">32-10</gadget>
<output>22</output>
22   ANSWER:22
<result>D</result>
Boxes numbered 1, 2, 3, 4 and 5 are kept in a row and they which are to be filled with either a red or a blue ball, such that no two adjacent boxes can be filled with blue balls. Then, how many different arrangements are possible, given that all balls of a given colour are exactly identical in all respects ?