A.The probability of drawing exactly 3 red marbles isfff\((x/(x+y+z))((x-1)/(x+y+z-1))((x-2)/(x+y+z-2))\)/fff
B.The probability of drawing at least 1 red marble isfff\(1-((y+z)/(x+y+z))((y+z-1)/(x+y+z-1))((y+z-2)/(x+y+z-2))\)/fff
C.The probability of drawing exactly 3 blue marbles isfff\((y/(x+y+z))((y-z)/(x+y+z-1))((y+z)/(x+y+z-2))\)/fff
我的答案：
