Delilah S.

asked • 09/09/20

Possible Combinations

Hi! I have to figure out how many possible combinations there are with 3 objects (square, circle, triangle), 3 per row. Also, 4 objects, 3 per row. Can you help me understand how you find the answer as well without having to write out all the possible combinations? Thanks so much!

Delilah S.

*3 objects, 4 per row. I apologize
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09/10/20

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Patrick B. answered • 09/09/20

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THere are 3 choices for the first object, 2 choices for the 2nd, and that leaves only 1 left...

3! = 3*2*1 = 6




Now choosing 3 out of 4 , you need the formula:

n! / [(k! (n-k)!]


4!/ (3!)(1!)

= 4*3!/3! = 4



{a,b,c,d} is the set

abc, abd, acd, bcd

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Delilah S.

My teacher said that for the first one it's 27 because the objects can repeat and can be in many orders. Ex. circle, circle circle; circle, circle, square; circle, square, circle; circle, square, square; circle, circle, triangle; circle, triangle, circle; circle, triangle, triangle etc. I'm not sure what that calculation would be considered as though. (It's 3x3x3 he said for 27 but I don't know why it is that. Hopefully this helps you come up with the calculations.) Also, for the second problem it's choosing 4 out of 3. Meaning, aaaa, aaab, etc.
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09/10/20

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