Shelease has a bag of 80 marbles. 10 are blue, 20 are red, and 8 are white. What are the chances of her getting white marbles.

Answer 1

P(1w)=8/80=1/10=10%

P(2w)=(1/10)(7/79)=7/790

P(3w)= (1/10)(7/79)(6/78)

P(4w)=.1(7/79)(6/78)(5/77)

P(5w)=.1(7/79)(6/78)(5/77)(4/76)

...

P(8w)=.1P(9)

P(>8w)=0

assuming the other 42 marbles are not white

80 total marbles

10+20+8 = 38 red,white&blue marbles

that leaves another 42 marbles, not r,w or b