SOLUTION: A box contains ten marbles, seven of which are black and three are red. Three marbles are drawn one after the other without replacement. Find the probability of choosing: a.

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Question 1158646: A box contains ten marbles, seven of which are black and three are
red. Three marbles are drawn one after the other without replacement. Find
the probability of choosing:
a. One red, one black and one red marble (in that order)
b. Two black marbles
c. At least two black marbles
d. At most two black marbles

Answer by VFBundy(438) About Me  (Show Source):
You can put this solution on YOUR website!
a. One red, one black and one red marble (in that order):

%283%2F10%29+%2A+%287%2F9%29+%2A+%282%2F8%29 = 42%2F720 = 7%2F120

b. Two black marbles:

%287C2+%2A+3C1%29%2F%2810C3%29 = = %2821+%2A+3%29%2F120 = 63%2F120 = 21%2F40

c. At least two black marbles:

%28%287C2+%2A+3C1%29+%2B+7C3%29%2F%2810C3%29 = = %28%2821+%2A+3%29+%2B+35%29%2F120 = %2863+%2B+35%29%2F120 = 98%2F120 = 49%2F60

d. At most two black marbles:

1+-+%287C3%2F%2810C3%29%29 = 1+-+%28%287%21%2F%283%21%2A4%21%29%29%29%2F%28%2810%21%2F%283%21%2A7%21%29%29%29 = 1+-+%2835%2F120%29 = 85%2F120 = 17%2F24