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If \ ^(20)C(r+1)=\ \ ^(20)C(r-1),\ t h e...

If `\ ^(20)C_(r+1)=\ \ ^(20)C_(r-1),\ t h e n\ r` is equal to a. 10 b. 11 c. 19 d. 12

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RD SHARMA ENGLISH-COMBINATIONS-All Questions
  1. If \ ^(20)Cr=\ ^(20)C(r+4),\ t h e n\ \ ^r C3 is equal to a. 54 b. 56 ...

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  2. If \ ^(15)C(3r)=\ \ ^(15)C(r+3)\ then\ r is equal to a. 5 b. 4 c. 3 d....

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  3. If \ ^(20)C(r+1)=\ \ ^(20)C(r-1),\ t h e n\ r is equal to a. 10 b. 11 ...

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  4. If C(n , 12)=C(n ,8),\ t h e n\ C(22 , n) is equal to a. 132 b. 210 c....

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  5. If \ ^m C1=\ \ ^n C2 then which is correct a. 2m=n b. 2m=n(n+1) c. 2m...

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  6. If \ ^n C(12)=\ \ ^n C8 then = a. 20 b. 12 c. 6 d. 30

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  7. If \ ^n Cr+\ ^n C(r+1)=\ \ ^(n+1)Cx ,\ t h e n x = a. r b. r-1 c. n d...

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  8. If \ ^(a^2-a)C2=\ \ ^(a^2-a)C4\ t h e n \ value\ of\ a\ is\ = a. 2 b....

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  9. \ ^5C1+\ ^5C2+\ ^5C3+\ ^5C4+\ ^5C5 is equal to a 30 b. 31 c. 32 d. 33

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  10. Total number of words formed by 2 vowels and 3 consonants taken from 4...

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  11. There are 12 points in a plane. The number of the straight lines joini...

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  12. There persons enter a railway compartment. If there are 5 seats vacant...

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  13. In how many ways can a committee of 5 be made out of 6 men and 4 women...

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  14. There are 10 points in a plane and 4 of them are collinear. The number...

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  15. There are 13 players of cricket, out of which 4 are bowlers. In how ...

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  16. The number of ways in which a host lady can invite for a party of 8 ou...

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  17. How many different committees of 5 can be formed from 6 men and 4 wome...

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  18. The number of diagonals that can be drawn by joining the vertices of a...

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  19. If \ ^(43)C(r-6)=\ ^(43)C(3r+1)\ then the value of r is a. 12 b. 8 c....

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  20. A lady gives a dinner party for six guests. The number of ways in whic...

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