document.write( "Question 1025309: a bag contains 15 identical discs.there are 8 red,4 blue and 3 white discs.A disc is picked out at random and not replaced.A second disc is then picked out at random and not replaced.A third disc is now picked out at random.Calculate the probability that none of the three discs is white. \n" ); document.write( "

Algebra.Com's Answer #640596 by Fombitz(32388) $\"\"$ $\"About$

You can put this solution on YOUR website!
Look at the possible outcomes.
\n" ); document.write( "RRR
\n" ); document.write( "RRW
\n" ); document.write( "RRB
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( ".
\n" ); document.write( "BBR
\n" ); document.write( "BBW
\n" ); document.write( "BBB
\n" ); document.write( "Out of the possible 27 outcomes, 9 start with a white chip.
\n" ); document.write( "Of the remaining 18 outcomes, 6 have a middle white chip.
\n" ); document.write( "Of the remaining 12 outcomes, 4 have a last white chip.
\n" ); document.write( "That leaves 8 outcomes that don't have a white chip.
\n" ); document.write( "RRR
\n" ); document.write( "RRB
\n" ); document.write( "RBR
\n" ); document.write( "RBB
\n" ); document.write( "BRR
\n" ); document.write( "BRB
\n" ); document.write( "BBR
\n" ); document.write( "BBB
\n" ); document.write( "Look at the occurences of R in the outcomes,
\n" ); document.write( "3 R=1
\n" ); document.write( "2 R=3
\n" ); document.write( "1 R=3
\n" ); document.write( "0 R=1
\n" ); document.write( " $\"P%283R%29=+%288%2F15%29%287%2F14%29%286%2F13%29+=336%2F2730+\"$
\n" ); document.write( " $\"P%282R%29=+%288%2F15%29%287%2F14%29%284%2F13%29+=224%2F2730+\"$
\n" ); document.write( " $\"P%281R%29=+%288%2F15%29%284%2F14%29%283%2F13%29+=96%2F2730+\"$
\n" ); document.write( " $\"P%280R%29=+%284%2F15%29%283%2F14%29%282%2F13%29+=24%2F2730+\"$
\n" ); document.write( "So then,
\n" ); document.write( " $\"P=+%28336%2B3%28224%29%2B3%2896%29%2B24%29%2F2730+\"$
\n" ); document.write( " $\"P=44%2F91\"$ \n" ); document.write( "

\n" );