Combination formula Watch

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may16
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#1
Report 16 years ago
#1
I am taking a Business Statistics class and I don't fully understand the steps in calaculating the combination formula.
What does the (!) represent?

This is the formula;

n^cr = n!/r!(n-r)!

I am having difficulty extrapolating this to:

7^c3 = n!/r!(n-r) = 7!/3!(7-3)! = 7!/3!4! = 35

What is being multiplied?
What is being divided?
What does (!) represent?
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#2
Report 16 years ago
#2
! stand for factorial and 7! means 7x6x5x4x3x2x1
Thus:
your question of
7!/3!x4! is actually:
(7x6x5x4x3x2x1)/(3x2x1)(4x3x2x1)=35

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