Question 191344: There are 10 houses in your neighborhood having a yard sale. You want to go to at least 5 of the houses having a yard sale. How many different combinations of yard sales can you attend?
My answer choices are:
A) 386
B) 638
C) 848
D) 1,286
E) 9,858,240
Answer by solver91311(24713) (Show Source):
You can put this solution on YOUR website!
For this you need combinations.
If you wanted to visit exactly 5 of the 10, the answer would be
But you want to visit at least 5, which means you may do 6, 7, 8, 9 or even all 10.
So, to you must add , , , , and
Man, that's a lot of arithmetic. I'm glad I don't have to do it. But here is a shortcut if you have MS Excel on your computer. Pick a cell on an empty spreadsheet and type in: =combin(10,5) then hit the enter key. You will get 252. Then copy the same thing to 5 adjacent cells and go back in and edit the second number to be 6, then 7 and so on. Then sum all 6 cells.
John

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