## Discussion Forum

Que. | Given a set of elements N = {1, 2, ..., n} and two arbitrary subsets A⊆N and B⊆N, how many of the n! permutations π from N to N satisfy min(π(A)) = min(π(B)), where min(S) is the smallest integer in the set of integers S, and π(S) is the set of integers obtained by applying permutation π to each element of S? |

a. | (n - |A ∪ B|) |A| |B| |

b. | (|A|^2+|B|^2)n^2 |

c. | n! |A∩B| / |A∪B| |

d. | |A∩B|^2nC|A∪B| |

Answer:n! |A∩B| / |A∪B| |