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16 marbles

Expert replies
by jkwan » Wed Jan 14, 2009 10:40 pm
A jar contains 16 marbles, of which 4 are red, 3 are blue, and the rest are yellow. If 2 marbles are to be selected at random from the jar, one at a time without being replaced, what is the probability that the first marble selected will be red and the second marble selected will be blue?

A. 3/64
B. 1/20
C. 1/16
D. 1/12
E. 1/8
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Source: — Problem Solving |

by Mr2Bits » Thu Jan 15, 2009 7:55 am
Im getting B but a little unsure.

8Y + 4R = 3B = 16M

Prob first is a red = 4/16 or 1/4

Prob second is 3/15 = 1/5

1/4 * 1/5 = 1/20
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by Hovey25 » Thu Jan 15, 2009 11:57 am
I agree B. 4/16 Red = 1/4. You are not replacing so the prob. of blue is 3/15.

1/4 * 1/5=1/20
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