DAT destroyer #89 error?

[joonkimdds]

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Find the number of ways that six objects A, B, C, D, E and F can be taken three at a time.

the solution says this is a permutation so 6x5x4 = 120
but I think this is combination, NOT permutation.
So i believe that the answer should be
6x5x4 / 6 = 20 (which is none of the choices)

Does anyone agree/disagree???

 

[artanis]

the order of the objects does not matter, so it is not a combination. an example of where to use combinations is if the 6 objects had to be ordered in 1st place, 2nd place and 3rd place in a competition. hope that helps.

 

[joonkimdds]

the order of the objects does not matter, so it is not a combination. an example of where to use combinations is if the 6 objects had to be ordered in 1st place, 2nd place and 3rd place in a competition. hope that helps.

I think u remember it in opposite way.
permutation = order matters
combination = order doesn't matter.

 

[PooyaH]

I think u remember it in opposite way.
permutation = order matters
combination = order doesn't matter.

Well you just justified it yourself!!! lol
ABC is NOT the same thing as CBA. So it makes sense to do premutation for this problem, doesn't it? But you might be right though, if that's all given for this problem; it's not specific enough!

 

[Aceofspades]

Well you just justified it yourself!!! lol
ABC is NOT the same thing as CBA. So it makes sense to do premutation for this problem, doesn't it? But you might be right though, if that's all given for this problem; it's not specific enough!

To the OP - I saw this question and thought the same exact thing.

To PooyaH - Three at a time should indicate that order does not matter. Think about grabbing 3 marbles at a time out of a bag of 6 marbles. There is no order, the marbles will just be in your hand and order will not matter. It is THREE AT A TIME... how can there be order when three are taken at the exact same time?

 

[doc3232]

Find the number of ways that six objects A, B, C, D, E and F can be taken three at a time.

the solution says this is a permutation so 6x5x4 = 120
but I think this is combination, NOT permutation.
So i believe that the answer should be
6x5x4 / 6 = 20 (which is none of the choices)

Does anyone agree/disagree???

I think it is 20...

 

[whoispittsnogle]

damn homey u love finding errors i just believe what the book says lol

 

[Lazerous]

I don't believe it is an error because the question exactly says:

"How many 3 letter license plates can be formed from the letters A, B, C, D, E, F, if each letter is to be used only once?"

Considering that they say "if each letter is to be used only once" I think it means order is important so it is a premutation.

Because a license plate that reads ABC is different than one that reads CBA.

 

[joonkimdds]

I don't believe it is an error because the question exactly says:

"How many 3 letter license plates can be formed from the letters A, B, C, D, E, F, if each letter is to be used only once?"

Considering that they say "if each letter is to be used only once" I think it means order is important so it is a premutation.

Because a license plate that reads ABC is different than one that reads CBA.

I guess that means they change the problem.
my DAT destroyer says
"Find the number of ways that six objects A,B,C,D,E, and F can be taken three at a time."

damn homey u love finding errors i just believe what the book says lol

I think it's becuz most of my DAT materials are old editions and I spend several hours to figure out if it's me who is wrong or them.

 

[Lazerous]

I guess that means they change the problem.
my DAT destroyer says
"Find the number of ways that six objects A,B,C,D,E, and F can be taken three at a time."


I think it's becuz most of my DAT materials are old editions and I spend several hours to figure out if it's me who is wrong or them.

Oh, if it is worded that way then I too would assume it was an nCr type problem.

 

[DrDentista]

order matters...permutation....

n!/ (n-r)!

 

[klutzy1987]

There are several poorly worded probability questions in the destroyer. However if you understandwhy your method is correct based on the way that you interpreted the question in the destroyer, you should be just fine.