SOLUTION: If someone can take only 4 out of 7 classes offered during the summer. How many different ways can she choose the classes she will take? I figured 4x7 is 28 but that answered

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Question 743130: If someone can take only 4 out of 7 classes offered during the summer. How many different ways can she choose the classes she will take?
I figured 4x7 is 28 but that answered, I was told, is incorrect. I'm trying to just write out all of the possible ways, but I know there has to be a formula of some type.
Thanks!!!
Found 2 solutions by checkley79, rothauserc:
Answer by checkley79(3341) About Me  (Show Source):
You can put this solution on YOUR website!
7*6*5*4=840 POSSIBLE OPTIONS.

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
The problem states:
If someone can take only 4 out of 7 classes offered during the summer. How many different ways can she choose the classes she will take?
This problem asks how many combinations are there of 7 items taken 4 at a time,
the formula is
7! / 4! * (7-4)! = 7*6*5*4 / 4*3*2*1 = 7*5 = 35 possible combinations