SOLUTION: Urn 1 contains 7 red balls and 4 black balls. Urn 2 contains 4 red balls and 1 black ball. Urn 3 contains 5 red balls and 3 black balls. If an urn is selected at random and a ball

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Question 1196711: Urn 1 contains 7 red balls and 4 black balls. Urn 2 contains 4 red balls and 1 black ball. Urn 3 contains 5 red balls and 3 black balls. If an urn is selected at random and a ball is drawn, find the probability that it will be red.
Found 2 solutions by math_helper, ikleyn:
Answer by math_helper(2461)   (Show Source):
You can put this solution on YOUR website!

Each urn is selected with probability so we multiply that by the probability of selecting red from each urn, and add them:

which works out to or about 0.687 (68.7% chance to pick red)
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EDIT: Oops, thanks tutor ikleyn. To check my answer, I had calculated the probability of obtaining black (0.313) and accidently copied down that calculation.

Answer by ikleyn(53937)   (Show Source):
You can put this solution on YOUR website!
.
Urn 1 contains 7 red balls and 4 black balls.
Urn 2 contains 4 red balls and 1 black ball.
Urn 3 contains 5 red balls and 3 black balls.
If an urn is selected at random and a ball is drawn, find the probability that it will be red.
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            I came to fix incorrect writing (typos ?) in the post by @math_helper.

P(red) = + + = = = = = = . ANSWER

Solved.