Question 1081073
When they say that each student has a different 
responsibility, it means there are 5 different jobs
on the committee, and the order of the same 5
people selected matters, as in:
1, 2, 3, 4, 5 is different from
2, 1, 3, 4, 5
so, permutations, not combinations are used
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P( 15, 5 ) = {{{ 15! / ( 15 - 5 )! }}}
P( 15, 5 ) = {{{ 15! / 10! }}}
P( 15, 5 ) = {{{ 15*14*13*12*11 }}}
P( 15, 5 ) = {{{ 360360 }}}
There are 360,360 ways to form a committee
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