Question

In how many ways 3 letters can be posted in 4 letter-boxes, if all the letters are not posted in the same letter-box.

• A. 63
• B. 60
• C. 77
• D. 81

Answer 1

Answer: (B)

60

Answer 2

Three letters can be posted in 4 letter boxes in $4^{3} = 64$ ways but it consists the 4 ways that all letters may be posted in same box. Hence required ways = 60.