document.write( "Question 1204025: An urn has 21 balls that are identical except that 5 are white, 9 are red, and 7 are blue. What is the probability that all are white if 3 are selected randomly without replacement?
\n" ); document.write( "
\n" ); document.write( "

Algebra.Com's Answer #840006 by ikleyn(52776)\"\" \"About 
You can put this solution on YOUR website!
.
\n" ); document.write( "
\r\n" );
document.write( "\r\n" );
document.write( "    P = \"C%5B5%5D%5E3%2FC%5B21%5D%5E3\" = \"10%2F1330\" = \"1%2F133\" = 0.007519...   ANSWER\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "The denominator is the number of all different sub-sets of 3 elements of the universal set of 21 balls.\r\n" );
document.write( "\r\n" );
document.write( "\r\n" );
document.write( "The numerator is the number of all different sub-sets of 3 white balls of the set of 5 white balls.\r\n" );
document.write( "
\r
\n" ); document.write( "\n" ); document.write( "Solved, with explanation.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "----------------\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "To see many other similar  (and different)  problems solved,  look into the lesson\r
\n" ); document.write( "\n" ); document.write( "    - Elementary Probability problems related to combinations \r
\n" ); document.write( "\n" ); document.write( "in this site.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Learn the subject from there.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "
\n" );