Question

There are $5$ white and $5$ black balls marked $1,2,....5$. In how many ways can these balls be arranged in a row so that balls of different colours are alternate?

Answer 1

$5$ white and $5$ black balls are there

For the ball to be alternate in colors possibilities are

$WBWBWBWBWB$

$BWBWBWBWBW$

So a number of ways are $5!\times 5!\times 2!=28800$