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Find the value of n in each of the follo...

Find the value of n in each of the following cases :
if `.^(20)C_(3n)=^(20)C_(2n+5)`

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The correct Answer is:
n=5orn=3
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CHHAYA PUBLICATION-PERMUTATION AND COMBINATION -EXERCISE 7B (Very Short Answer Type Questions )
  1. Explain the concept of permutation and combination.

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  2. Find the value of n in each of the following cases : if .^(n)C(n-2)...

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  3. Find the value of n in each of the following cases : if .^(n)C(n-4...

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  4. Find the value of n in each of the following cases : if .^(2n)C(4):...

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  5. Find the value of n in each of the following cases : if .^(n)C(5)=^...

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  6. Find the value of n in each of the following cases : if .^(20)C(3n)=...

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  7. If .^(n)C(7)=^(n)C(11) , show that .^(21)C(n)=1330.

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  8. If .^(n)P(r)=120xx.^(n)C(n-r), find the valueof r.

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  9. If .^(2n)C(r)=.^(2n)C(r+2) find the value of r.

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  10. If .^(n)C(4)=21xx.^(n/2)C(3) , find the value of n.

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  11. How many different triangles can be formed by joining the angular poin...

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  12. n points are in space ,no three of which are collinear .if the number...

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  13. Out of 9 Swarajists and 5 Ministrialists , how many different committe...

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  14. In how many different ways cann a committee of 5 boys and 3 girls can...

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  15. In how many ways can 3 mangoes be selected from 10 mangoes so as to a...

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  16. A man has 6 friends .how many ways can be invite one or more of them t...

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  17. In how many ways can a person contribute to a charitable fund out of 1...

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  18. How many different factors can 2310 have ?

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  19. At a certain examination , there are 8 papers . In order to pass the ...

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  20. The Indian Cricket XI is to play 5 test matches against M.C.C Cricket...

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