Engineering Board Exam Reviewer · Permutations · medium

In how many ways can 3 boys and 3 girls be arranged in a row so that boys and girls alternate?

  1. 72
  2. 36
  3. 720
  4. 144

Answer

A. 72

Solution

The row can start with a boy or a girl (2 ways). The 3 boys can be arranged in 3!=6 ways and the 3 girls in 3!=6 ways. Total =2×6×6=72.

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