In how many ways can 10 postcards be posted into 6 letterboxes ?
a) 10^6
b) 6^10
c) 10C6(10)
d) 10P6
e) 10P6(6)
OA b
a) 10^6
b) 6^10
c) 10C6(10)
d) 10P6
e) 10P6(6)
OA b
Hey Gughan,
This is a weird sort of combinatorics question, which I would solve with the slots method:
1. Find # of slots (decisions to be made)
2. Fill in possibilities at each decision point
3. Figure out if Order matters or not (or a hybrid)
4. If order matters, multiply all slots together; if order doesn't matter, multiply all slots and divide by # of slots factorial wherever order doesn't matter.
In this case, we have to make 10 decisions, because every postcard has to be mailed. We need to decide which of the 6 mailboxes to put each mailbox in.
_ _ _ _ _ _ _ _ _ _
For each postcard, we have 6 choices. This pool never drops down (as it does in most combinatorics questions), because there's no limit to how many postcards we can put in each letterbox:
6 6 6 6 6 6 6 6 6 6
The answer is thus [spoiler]6^10[/spoiler].
-t
