Hello candidate,

In The question you had mentioned that there are 5 black 6 white and 7 red balls, from which 4 balls are needed to be drawn and X denotes the number of white balls drawn in several attempts.

There can be several cases,

Let X equal to 1, so the total ways of drawing are- 6C1 × 12C3.

Let X equal to 2, the total number of ways of drawing are- 6C2 × 12C2.

Let X equal to 3, the total number of ways of drawing are- 6C3 × 12C1.

Let X Equal to 4, the total number of ways of drawing are- 6C4.

Hope This answer was helpful!!