<PRE><B>Question 1120232</B>
The P( 2 or more girls on committee of 3 ) is
1 minus P( no girls on committee AND 1 girl on committee )
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The number of possible committees formed with no girls is:
C( 12, 3 ) = {{{ 12! / ( ( 12 - 3 )! * 3! ) }}}
{{{ 12! / ( 9! * 3! ) = ( 10*11*12 ) / ( 3*2 ) }}}
{{{ 10*11*2 = 220 }}}
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Possible committees with 1 girl is:
C( 12, 2 )*8 = {{{ ( 12! / ( 10! * 2! )) * 8 }}}
{{{ (( 11*12 ) / 2 ) * 8 }}}
{{{ 66*8 = 528 }}}
and
{{{ 220 + 528 = 748 }}}
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the total possible committees is:
C( 20, 3 ) = {{{ 20! / ( 17! * 3! ) }}}
{{{ ( 18*19*20 ) / ( 3*2 ) }}}
{{{ 3*19*20 = 1140 }}}
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P( at least 2 girls ) = {{{ 1  - 748 / 1140 }}}
{{{ 1 - .6561 = .3439 }}}
Get a 2nd opinion on this definitely
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