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The number of all three element subse...

The number of all three element subsets of the `{a_1,a_2 ,a_3 ,… a_n}` which contain `a_3 ` is

A

`"""^(n)C_(3)`

B

`""^(n-1)C_(2)`

C

`2^(n-2)`

D

`2^(n)`

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The correct Answer is:
B
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DIPTI PUBLICATION ( AP EAMET)-PERMUTATIONS & COMBINATIONS-EXERCISE 1B (COMBINATIONS )
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  2. The number of subesets contining atmost 5 elements that can be...

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  3. The number of all three element subsets of the {a1,a2 ,a3 ,… an}...

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  4. The number all three element ofsubsets of the set A = {a1 ,a2 , . ....

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  5. If one quarter of all three element subsets of the set A = { a1...

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  7. If a set A has 5 elements , then the number of ways of selectin...

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  8. Given 5 different green dyes 4 different blue dyes and 3 diffe...

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  10. A Fruits basket contains 4 organes , 5 apples and 6 mangoes ....

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  12. The number of positive divisors of 2 ^5 , 3^6 ,7^3 is

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  13. The number of all positive divisors of 2 ^5 , 3^4 , 5^3 is

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  14. The number of positive divisors of 2520 is

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  15. The number of divisors of 7! is

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  16. The number of ways in which 1800 can be divided into two fact...

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  17. The number of ways in which 1440 can be divided into two fact...

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  18. The number of positive odd divisors of 216 is

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  19. The number of even divisors of 1600 is

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  20. The number of odd factors of 36000 is

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