Question 191392This question is from textbook MATHEMATICS: Structure and Method, Course 2
: I DON'T KNOW WHAT TO DO! HELP ME HERE IS THE QUESTION-
Philip wishes to check out two books out of his school library. If the library contains 800 books, in how many ways might Philip get his choice of books?
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This question is from textbook MATHEMATICS: Structure and Method, Course 2
Found 2 solutions by Alan3354, jim_thompson5910:
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! Philip wishes to check out two books out of his school library. If the library contains 800 books, in how many ways might Philip get his choice of books?
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His 1st selection is 1 of 800. The 2nd is 1 of 799.
That's 800*799 = 639200 ways.
But, if he picks book A and book B, it's the same as picking book B then book A, so it's 800*799/2
= 319600 possibilities.
Answer by jim_thompson5910(35256)  (Show Source):
You can put this solution on YOUR website! For the first selection, you have a choice of 800 books. Once that selection has been made, you now have 799 books left over. So if the order matters, then you simply multiply 800 by 799 to get:
800 x 799 = 639,200
So there are 639,200 different ways to choose two books (where the order of the books matters).
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If the order of the books does NOT matter, then simply divide by 2 (since xy is the same as yx) to get
639,200/2=319,600
So there are 319,600 different ways to choose two books if the order does NOT matter.
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