I'm posting one puzzle, riddle, math, or statistical problem a day. Try to answer each one and post your answers in the comments section. I'll post the answer the next day. Even if you have the same answer as someone else, feel free to put up your answer, too!
Thursday, October 11, 2007
Going to the Show?
A theater has five entrances. In how many ways can you enter and leave by a different entrance?
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Mmmm...combinations and permutations...
ReplyDelete5 entrance choices, 4 exit choices per entrance choice. 5 times 4 = 20 ways.
Or, since you have a group of five, and you're choosing 2, and order DOES matter, you use the permutations formula:
nPr = n!/(n-r)! = 5!/3! = 20
you could go in and out the same way...?
ReplyDeleteactually, nick, the question specifies "by a different entrance"...
ReplyDeleteLooks like Abe covered it all. 20 is the answer.
ReplyDelete