Write the number of ways in which 12 boys may be divide into three groups of 4 boys each.

Number of groups in which 12 boys are to be divided = 3

Now 4 boys can be chosen out of 12 boys in (¹²C₄⁸C₄⁴C₄) ways.

=

These groups can be arranged in 3! ways.

Total number of ways =

= 5775