Correct Answer - B
7 white and 3 black balls can be arranged in a row in
10!
3!7!
ways.
When 7 white balls are arranged in a row there are 8 place in between. In these 8 places 3 black balls can be arranged in .8C3
ways.
∴
Required probability =
.8C3
10!
3!7!
=
7
15