Permutation and CombinationMedium
Question
Which of the following statement(s) is/are true :-
Options
A.100C50 is not divisible by 10
B.n(n - 1) (n - 2) ............ (n - r + 1) is always divisible by r! (n ∈ N and 0 ≤ r ≤ n)
C.Morse telegraph has 5 arms and each arm moves on 6 different positions including the position of rest. Number of different signals that can be transmitted is 56 - 1.
D.There are 5 different books each having 5 copies. Number of different selections is 65 - 1.
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