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## #1 2007-10-08 00:26:07

ganesh
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### Permutations and Combinations Vol.I

1. Find the total number of 9 digit numbers which have all different digits.

2. From 12 mathematicians and 9 physicists, a committee of 8 is to be formed including two physicists. The committee can consist of 2 physicists and 6 mathematicians. In how many ways can the committee be chosen so as to give a majority to mathematicians?

3. 20 persons were invited for a party. In how many ways can they and the host be seated at a circular table? In how many of these ways will two particular persons be seated on either side of the host?

4. m men and n women are to be seated in a row so that no two women sit together. If m>n, show that the number of ways in which they can be seated is
[m!(m+1)!]/(m-n+1)!.

5. Find the number of diagonals which can be obtained by joining the vertices of a polygon of n sides. How many triangles can be formed by joining the vertices of the polygon?

6. If p parallel straight lines are intersected by q parallel straight lines, then the number of parallelograms formed is
(a) (pq)/4     (b)(p-1)(q-1)/4    (c)pq(p-1)(q-1)/4  (d) None of these.

7. If nC4=126, then the value of nP4 is
(a)2564    (b) 3024    (c) 6050   (d) None of these

8. If 2nC3:nC2=44:3, then the value of n is
(a)3    (b)5      (c)6      (d) None of these

7. If nCr-1=356, nCr=84 and nCr+1=126, then r is equal to:
(a)1   (b)   2     (c) 3    (d) None of these

8.From 6 gentlemen and 4 ladies, a committee of five can be formed in
(a)200 ways  (b)252 ways   (c)260 ways   (d)300 ways

Character is who you are when no one is looking.

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