SOLUTION: One urn contains 3 red and 7 white marbles. A second urn contains 2 red and 8 white marbles. One urn is selected and a ball drawn. The probability of selecting the first urn i

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Question 94936:
One urn contains 3 red and 7 white marbles. A second urn contains 2 red and 8 white marbles. One urn is selected and a ball drawn. The probability of selecting the first urn is 0.4 and the probability of selecting the second is 0.6. If a white ball is drawn, find the probability it came from the second urn.

Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
Urn#1 .4*.7=.28
Urn#2 .6*.8=.48
.28+.48=.76
Notice that the probabilities don't add up to 1.00
That's because we have excluded the possibility of getting a red ball from either of the urns. (the missing .24)
.48%2F.76=12%2F19probability the ball came from urn#2
EdJones