SOLUTION: For a class field trip, 12 parents volunteered to be the chaperones. If a group of 5 parents is needed for the trip, how many groups can be chosen? SHOW YOUR WORK

Algebra ->  Probability-and-statistics -> SOLUTION: For a class field trip, 12 parents volunteered to be the chaperones. If a group of 5 parents is needed for the trip, how many groups can be chosen? SHOW YOUR WORK      Log On


   

Question 1082313: For a class field trip, 12 parents volunteered to be the chaperones. If a group of 5 parents is needed for the trip, how many groups can be chosen? SHOW YOUR WORK
Found 2 solutions by josmiceli, jorel1380:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
For any given group, the order is unimportant.
This means combinations and not permutations
are used.
C( 12,5 ) = +12%21+%2F+%28+5%21%2A%28+12-+5+%29%29%21+
+12%21+%2F+%28+5%21%2A7%21+%29+
+%28+12%2A11%2A10%2A9%2A8+%29+%2F+%28+5%2A4%2A3%2A2%2A1+%29+
+95040+%2F+120+=+792+
There are 792 ways to choose different groups
of 5 parents from 12 volunteers

Answer by jorel1380(3719) About Me  (Show Source):
You can put this solution on YOUR website!
12 parents, chosen 5 at a time, equals 12 choose 5, or 792. Checking to see, we get:
12 choose 5=12!/7!5!=12x11x10x9x8x7!/5x4x3x2x1x7!=95040/120=792 ☺☺☺☺