Three people draw lots in groups.

p(B)=(4/ 10)*(3/9)+(6/ 10)*(4/9)= 4/ 10。

p(C)=(4/ 10)*(3/9)(2/8)+(6/ 10)*(4/9)+(6/ 10)*(5/9)。

This is a fair draw principle, so no matter which draw, the difficulty of drawing is the same.

If the four difficult items are replaced by the first prize, that is to say, the lottery probability of different rounds is the same.