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leehuan

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Really just going to be perms and combs whatever I put here, anyway


Five letters are chosen from the letters of MOBILITY. These five letters are then placed alongside each other to form a five letter arrangement. How many arrangements are possible?
 

InteGrand

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Really just going to be perms and combs whatever I put here, anyway


Five letters are chosen from the letters of MOBILITY. These five letters are then placed alongside each other to form a five letter arrangement. How many arrangements are possible?










 

leehuan

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Hang on, having a mind blank. Why is it 5C2 for the arrangements of the two I's in Case 1 again?
 

InteGrand

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Hang on, having a mind blank. Why is it 5C2 for the arrangements of the two I's in Case 1 again?
The words consist of five letters: _ _ _ _ _.

Since in Case 1, we are having 2 I's, and I's are identical, we just choose the positions for them to go, which is done in 5C2 ways (from the 5 spaces, choose 2 for the I's to occupy).
 

leehuan

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The words consist of five letters: _ _ _ _ _.

Since in Case 1, we are having 2 I's, and I's are identical, we just choose the positions for them to go, which is done in 5C2 ways (from the 5 spaces, choose 2 for the I's to occupy).
Oh of course. That was nice and easy enough; must've forgotten something. Thanks.
 

calamebe

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Hang on, having a mind blank. Why is it 5C2 for the arrangements of the two I's in Case 1 again?
We have 5 spots to put them, and we need to put 2 I's in the places, and the order does not matter as they are the same letter.

Nevermind beat me to it.
 

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