document.write( "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. \n" ); document.write( "

Algebra.Com's Answer #829686 by math_helper(2461) $\"\"$ $\"About$

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document.write( "Each urn is selected with probability  so we multiply that by the probability of selecting red from each urn, and add them:\r
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document.write( "which works out to   or about 0.687  (68.7% chance to pick red)\r
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document.write( "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.   \n" );
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