document.write( "Question 1151293: An urn contains 4 balls numbered 0 through 3. One ball is selected at
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\n" ); document.write( "numbers less than that of the selected ball are also removed from the urn.
\n" ); document.write( "Then a second ball is selected at random from those remaining in the urn.
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Algebra.Com's Answer #773024 by math_helper(2461) $\"\"$ $\"About$

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document.write( "The first selection from {0,1,2,3} is  1/4  for each ball.  Now we need to look at what happens for each of these selections:\r
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document.write( "First           Sample space        
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document.write( "selection       for 2nd selection          Pr{2nd pick is 3} 
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document.write( "----------      -----------------          -----------------
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document.write( "    0              {1,2,3}                  (1/4)(1/3)
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document.write( "    1              {0,2,3}                  (1/4)(1/3)
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document.write( "    2              {0,3}                    (1/4)(1/2)
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document.write( "    3              {0}                      (1/4)(0)\r
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document.write( "Adding up all the probabilities for a 3 on 2nd pick:  
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document.write( "or about 29.2%\r
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document.write( "Check:
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document.write( " The other numbers probabilities:  Pr{0} = 11/24, Pr{1} = 2/24, Pr{2} = 4/24\r
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document.write( " Adding these should give 1:  (11+2+4+7)/24 = 24/24 = 1  (ok)\r
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