Question

Which of these expressions is equivalent to 15C3? a) 15C12 b)12C15 c) 15C18 d) 18C15

Answer 1

it’s A: 15c12 :)) have a great day love

Answer 2

Answer: Choice A

15C12

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Reason:

Imagine there are 15 students and we wish to form a committee of three people, where order doesn't matter. The answer to this problem is 15C3 using the nCr formula. Here n = 15 and r = 3.

The 15C3 represents the number of ways to pick the three people on the committee, while 15C12 is the number of ways to not pick a person for the committee. We can think of it like two separate committees if you want.

So 15C3 = 15C12

The numbers after the "C" add to the value of n

The identity is
`_nC_r = _nC_(n-r)`

The r and n-r add to n.