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#1 2006-12-31 11:11:34

Toast
Real Member
Registered: 2006-10-08
Posts: 1,321

Major Typo or...?

A student attempts a True/False quiz consisting of 10 questions. The teacher has told the student that for five of the questions the answer is 'T' whilst for the other five questions the answer if 'F'. In how many different ways can the student assign answers to the questions if he knows the answers to the questions alternate between true and false?
(Answers say 28000)

Now obviously if there are 5 true answers and 5 false answers there are only 2 arrangements.... riiiight?

T F T F T F T F T F
and
F T F T F T F T F T

I really don't think the book woulda made such a huge typo however; is there any way you think one might reach 28000?

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#2 2006-12-31 15:29:25

pi man
Member
Registered: 2006-07-06
Posts: 251

Re: Major Typo or...?

With the stipulation that the answers alternate between True and False, there are only the 2 solutions you mentioned.

Even if  you remove that restriction, there are only 252 (10 choose 5) ways to arrange the 5 True's and 5 False's.  And even if you remove the restriction of 5 True's and 5 False's, there are only 1024 ways to complete the exam (2^10).   

So it's definitely a typo.

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#3 2007-01-01 09:19:25

krassi_holmz
Real Member
Registered: 2005-12-02
Posts: 1,905

Re: Major Typo or...?

I really don't think the book woulda made such a huge typo however; is there any way you think one might reach 28000?

Yep.
If the test consisted 1 question with 28000 answers and the student didn't knew anything smile

Last edited by krassi_holmz (2007-01-01 09:20:51)


IPBLE:  Increasing Performance By Lowering Expectations.

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