Question

Whats the value of 13C11

Answer 1

78

Explanation:

`nC_k = (n!)/(k!(n-k)!)`

`13 C_(11) = (13!)/(11! * (13-11)!)`

`= (13!)/(11! * 2!)`

`= ( 1 * 2 * 3 * 4 * 5 * 6 * 7 * 8 * 9 * 10* 11 * 12 * 13)/((1 * 2 * 3 * 4 * 5 * 6 * 7 * 8 * 9 * 10* 11 )* ( 1 * 2))`

`=(12 * 13)/(2) \\\\= 6 * 13\\\\=78`