on how many nights may a watch of 4 men be drafted from a crew of 24, so that no two watches are identical On how many of would any one man be taken?

Explanation

Since, we are selecting 4 men so that no two watches are identical.
So, we need to select different men.

The number of ways of selecting 4 different men from 24, we get


=`24_(C_4)
=10626`

One man is being always included, thus select 3 men from 23

The number of ways of selecting 3 different men from 23 men is


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