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Question stem: We are asked to find (n-m)C12
1 - Sufficient.
(n-m+1)C12 = 13
(n-m+1)! / (n-m-11)!*12! = 13
(n-m+1)*(n-m)! / (n-m-11)!*12! = 13
Since 13 is a prime number, only n-m = 12 can solve this eqn.
So, sufficient.
To prove (or disprove), take n-m=13, we have 14*13! / 2*12! = 14*13/2
not equal to 13.
2 - sufficient.
n-m = 12, so we can find (n-m)C12
Hence D
1 - Sufficient.
(n-m+1)C12 = 13
(n-m+1)! / (n-m-11)!*12! = 13
(n-m+1)*(n-m)! / (n-m-11)!*12! = 13
Since 13 is a prime number, only n-m = 12 can solve this eqn.
So, sufficient.
To prove (or disprove), take n-m=13, we have 14*13! / 2*12! = 14*13/2
not equal to 13.
2 - sufficient.
n-m = 12, so we can find (n-m)C12
Hence D