Question

Question #3a2dc

Answer 1

`840`

Explanation:

If AAABCDE were unique elements, the the number of permutations would be:

`7! =5049`

Since we have 3 indistinguishable elements we have to divide these out:

`(7!)/(3!) = 840`

This is quite logical if you consider that 7! would contain all the permutations of the following:

AAA

These are not distinguishable from each other, and the number of permutations of this is 6 i.e. 3! which is what we divided out.