In how many ways can 5 letters be posted in 3 post boxes, if any number of letters can be posted in all of the three post boxes?  Choose the correct choice:
A) 152
B) 3^5
C) 125
D) 217
E) 136
The first letter can be posted in any of the 3 post boxes. Therefore, we have 3 possibilities.   Similarly, the second, the third, the fourth and the fifth letter can each be posted in any of the 3 post boxes.   Each of the 5 letters has 3 possibilities because we can post any number of letters in all of the boxes.   Therefore, the total number of ways the 5 letters can be posted in 3 boxes is   3 * 3 * 3 * 3 * 3 = 3^5   Ans: 3^5
<result>B</result>
In how many ways can 5 letters be posted in 3 post boxes, if any number of letters can be posted in all of the three post boxes?