Question 1002206: given 4 distinct objects, if 2 objects are taken at the time, the possible number combinations is equal 2. True or false?
*note: I used the combination formula nCr and I got 2. So "False." Just wanted to be sure if it was the right application I made. Thank you
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! nCr formula is n! / (r! * (n-r)!
4C2 formula becomes 4! / (2! * (4-2)! which becomes 4! / (2! * 2!) which becomes (4*3*2!) / (2!*2!) which becomes (4*3)/2! which becomes 6.
your answer should have been 6.
let the 4 distinct objects be a, b, c, d
the possible combinations, taken 2 at a time, are:
ab
ac
ad
bc
bd
cd
that's 6 possible combinations.
you used the correct formula, but you must have applied it wrong, or you explained it wrong.
4C2 = 4! / (2! * 2!) = (4*3*2*1) / (2*1*2*1)
get rid of the 1's because they don't add anything to it, and you get:
4C2 = (4*3*2) / (2*2) which becomes (4*3*2) / 4 which becomes 3*2 = 6
false is the correct answer because 6 is not equal to 2.
your last statement, however, doesn't make sense because you say:
*note: I used the combination formula nCr and I got 2. So "False." Just wanted to be sure if it was the right application I made. Thank you
if you got 2, then you should have said true.
perhaps you meant you didn't get 2?
you got the answer right but your explanation was confusing.
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