China Naming Network - Ziwei knowledge - 10'' There are four difficulties in drawing lots, three people draw lots for the exam, A first, B second, C finally, and then find the probability that each of them is difficult to sign.
10'' There are four difficulties in drawing lots, three people draw lots for the exam, A first, B second, C finally, and then find the probability that each of them is difficult to sign.
P (A) =4/ 10
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.