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If n persons are sitting in a row, find ...

If n persons are sitting in a row, find the number of ways of selecting two persons, who are sitting adjacent to each other.

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`=n-1`
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VIKRAM PUBLICATION ( ANDHRA PUBLICATION)-PERMUTATIONS AND COMBINATIONS-TAXTUAL EXERCISES
  1. If ""^(n)P(4)=210, find n.

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  2. If ""^(12)C(r)=495, find the possible values of (r ).

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  3. If ""^(n)P(r)=5040 and ""^(n)C(r)=210, find n and r.

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  4. If ""^(n)C(4)=""^(n)C(6), find n.

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  5. If ""^(17)C(2t+1)=""^(17)C(3t-5), find t.

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  6. If ""^(9)C(3)+""^(9)C(5)=""^(10)C(r) then find r.

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  7. Find the number of ways of forming a committee of 5 members from 6 men...

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  8. Find the number of ways of forming a committee of 5 members from 6 men...

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  9. Prove that for 3 le" r " le n, ""^((n-3))C(r)+.""^((n-3))C((r-1))+3....

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  10. Find the number of ways of selecting 3 girls and 3 boys out of 7 girls...

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  11. Find the number of ways of selecting a committee of 6 members out of 1...

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  12. Find the number of ways of selecting 5 books from 9 different mathemat...

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  13. Find the number of diagonals of a polygon with 12 sides.

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  14. If n persons are sitting in a row, find the number of ways of selectin...

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  15. Find the number of ways of giving away 4 similar coins to 5 boys if ea...

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  16. Prove thaty (""^(4n)C(2n))/(""^(2n)C(n))=(1.3.5…..(4n-1))/({1.3.5…..(2...

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  17. Find the numbers of ways of selecting a cricket team of 11 players fro...

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  18. If 5 vowels and 6 consonants are given, then how many 6 letter words c...

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  19. Find the number of ways in which 12 things be (i) divided into 4 equal...

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  20. A class contains 4 boys and g girls. Every Sundy, five students with a...

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