Peanuts by Charles Schulz for May 07, 1974
May 06, 1974
May 08, 1974
Transcript:
Peppermint Patty sits at her desk in school and reads a book. She reads, "A library shelf contains seven books."<BR><BR> Peppermint Patty continues to read, "Three books are math books and four books are science books . . ."<BR><BR> Peppermint Patty reads, "Problem: In how many ways may the books be arranged on the shelf so that all the math books will be together?"<BR><BR> Peppermint Patty shouts, "Defense! Defense!"<BR><BR>
gamer2k4 over 11 years ago
The answer is five, right?
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empireatwar over 7 years ago
Why is she saying, “Defense! Defense!”?
All... over 4 years ago
This one is pretty easy (assuming the question sees all of one type of book as being the exact same book and not, for instance, different volumes). Because all the math books have to be together, they can be treated as a single unit, which leaves you with only 5 positions (4 science books + 1 set of math books), and, because only one of the objects in those positions is unique, that means there are exactly 5 permutations/arrangements.
Stormwyrm over 3 years ago
There are three math books, so there are 3! = 6 ways of arranging them. There are four science books, so there are 4! = 24 ways of arranging them. For each way of arranging the science books there are three ways of putting the math books between them, and it is also possible to put the math books before them and after them, so there are five total ways. Thus the number of ways to arrange the books so that the math books are always together is 24 × 5 × 6 = 720.
thatdarnfurry over 2 years ago
I only got 1 way. Group the maths books together then put the science ones next to them