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CGP EDU Academic Team
Published on: August 14, 2026
The number of functions f from {1, 2, 3, …., 20}, onto {1,2,3,………..,20} such that f(k) is a multiple of 3, wherever k is a multiple of 4, is
Text Solution
Verified by ExpertsThe correct answer is:
B
Sol. k = {4, 8, 12, 16, 20}
f(k) can take values from set {3, 6, 9, 12,15,18} this can be done is 
ways. = 6! ways
and options for remaining 15 elements of A = 15
∴ Total number of onto functions = 6! 15!
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