Question

A signal can be formed by running different colored flags up a​ pole, one above the other. find the number of different signals consisting of 7 flags that can be made using 3 white​ flags, 2 red​ flags, and 2 blue flags.

Answer 1

$\dfrac{7!}{3!2!2!}=\dfrac{4\cdot5\cdot6\cdot7}{2\cdot2}=210$