Combinatorics

JEE Main 2015 Discussion Forum › Algebra questions › Combinatorics

Q) Find the no. of three elements sets of positive integers ( a,b,c ) such that a*b*c = 2310.

Q) Find the no. of integers between 1 and 10000 with at least one 8 and at least one 9 as digits.

#Mathematics #Algebra

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6 Answers

341

Hari Shankar ·2011-03-08 01:23:02

@ninepointcircle - 231 is not a prime :D

post #11 at http://www.targetiit.com/iit-jee-forum/posts/combinatorics-18476.html

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ninepointcircle ·2011-03-08 01:51:52

sry
i didnt saw it
the nit has to be solved by stirling number concept ..u can see it on wiki
the answer will be 1+ S(5,2)+S(5,3) = 41

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71

Vivek @ Born this Way ·2011-03-08 03:22:07

Sir, That page has still three unsolved problems.

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aieeee ·2011-03-08 06:08:38

Got d 1st one. plz try the 2nd one out.

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Vivek @ Born this Way ·2011-03-09 08:52:07

Well, I can give some hints of course you try it out:

First 1 digit nos: Not possible
2 digit Nos.: 89,98 so 2 numbers
3 digit No: 2* 3!2!

and so on.. only upto 4 digits.. think

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Abhisek ·2011-03-24 22:35:27

Hey is the answer of the 2nd question 1200 ?

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Your Answer

Basic Integral Calculus Operators Symbols Matrix Cases

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