NSEA · Mathematics

Permutations and Combinations

Counting principles, nPr/nCr and elementary combinatorial reasoning.

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  • Q1 · Permutations and Combinations · EASY

    The number of ways to arrange 4 distinct objects in a row is:

  • Q2 · Permutations and Combinations · MEDIUM

    A team of 6 astronomers is to be selected from 5 men and 4 women such that the team must have at least 2 women. How many different teams can be formed?

  • Q3 · Permutations and Combinations · EASY

    The number of ways in which 5 different books can be arranged on a shelf such that two particular books are always together is:

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