Question

18. There are four boxes and four balls each of colours Red, Blue, Green and White. Each ball is put in a box such that no box has a ball of its colour. The minimum number of boxes to be opened such that we can identify which coloured ball is in
which coloured box, is

(1) 1
(2) 2
(3) 3
(4) 4​

Answer 1

Answer:

There are four balls of different colours and four boxes of colours same as those of the balls. The number of ways in which the balls, one each in a box ...