document.write( "Question 1178901: Construct a valid probability distribution for the number of boys a couple could have if they were to have 4 children.\r
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Algebra.Com's Answer #808368 by Edwin McCravy(20055)\"\" \"About 
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document.write( "There are 16 ways their 4 children could turn out, all assumed equally likely:\r\n" );
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document.write( "    ways   number of boys\r\n" );
document.write( " 1. BBBB         4\r\n" );
document.write( " 2. BBBG         3\r\n" );
document.write( " 3. BBGB         3\r\n" );
document.write( " 4. BBGG         2\r\n" );
document.write( " 5. BGBB         3\r\n" );
document.write( " 6. BGBG         2\r\n" );
document.write( " 7. BGGB         2\r\n" );
document.write( " 8. BGGG         1\r\n" );
document.write( " 9. GBBB         3\r\n" );
document.write( "10. GBBG         2\r\n" );
document.write( "11. GBGB         2\r\n" );
document.write( "12. GBGG         1\r\n" );
document.write( "13. GGBB         2\r\n" );
document.write( "14. GGBG         1\r\n" );
document.write( "15. GGGB         1\r\n" );
document.write( "16. GGGG         0\r\n" );
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document.write( "So there are 5 numbers of boys, that X can take on, 0 through 4.\r\n" );
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document.write( "1 way  to have 0 boys out of 16 ways to have 4 children.\r\n" );
document.write( "4 ways to have 1 boy out of 16 ways to have 4 children.\r\n" );
document.write( "6 ways to have 2 boys out of 16 ways to have 4 children.\r\n" );
document.write( "4 ways to have 3 boys out of 16 ways to have 4 children.\r\n" );
document.write( "1 way  to have 4 boys out of 16 ways to have 4 children.\r\n" );
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document.write( "So the answer is:\r\n" );
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document.write( "    X   p(X)\r\n" );
document.write( " 1. 0   1/16\r\n" );
document.write( " 2. 1   4/16 reduces to 1/4\r\n" );
document.write( " 3. 2   6/16 reduces to 3/8\r\n" );
document.write( " 4. 3   4/16 reduces to 1/4\r\n" );
document.write( " 5. 4   1/16\r\n" );
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document.write( "Notice that the sum of all the probabilities is 16/16  = 1.\r\n" );
document.write( "None are negative.\r\n" );
document.write( "None are greater than 1.\r\n" );
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document.write( "Edwin
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