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Find the number of permutations of 7 obj...

Find the number of permutations of `7` objects, taken `3` at a time.

A

` ""^(7)P_(3)`

B

` ""^(7)C_(3)`

C

` ""^(7)P_(3)7!`

D

` ""^(7)P_(3)3!`

Text Solution

Verified by Experts

The correct Answer is:
A
Number of permutations of 7 objects, taken 3 at a time
`= ""^(7)P_(3) = 7xx6xx5 " " `[up to three terms]
`=210.`
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RS AGGARWAL-PERMUTATIONS-SOLVED EXAMPLES
  1. Prove that: (i) ""^(n)P(n)=""^(n)P(n-1) " (ii) "^(n)P(r)=n* ""^...

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  2. If r lt s le n " then prove that " ^(n)P(s) " is divisible by "^(n)P(r...

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  3. Find the number of permutations of 7 objects, taken 3 at a time.

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  4. Find the number of different permutations of the letters of the word ...

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  5. How many words can be formed using the letter A thrice, the letter B ...

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  6. (i) Find how many arrangements can be made with the letters of the wo...

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  7. Find the number of arrangements of the letters of the INDEPENDENCE....

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  8. How many different words can be formed by using all the letters of the...

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  9. In how many of the distinct permutations of the letters in MISSISSIPPI...

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  10. (i) How many words can be formed with the letters of the word, 'HARYAN...

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  11. In how many ways can the letters of the word 'PERMUTATIONS' be arrang...

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  12. If the different permutations of all the letter of the word EXAMINATIO...

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  13. Find the number of words with or without meaning which can be made ...

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  14. How many numbers greater than a million can be formed with the digits ...

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  15. How many numbers greater than 400000 can be formed by using the digit...

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  16. How many numbers can be formed using the digits 1, 2, 3, 4, 3, 2, 1 so...

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  17. In how many ways can 4 letters be posted in 3 letter boxes?

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  18. In how many ways can 6 different rings be worn in 4 fingers of the han...

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  19. In how many ways can 5 apples be distributed among 6 boys, there being...

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  20. In how many ways can 3 prizes be distributed among 4 boys, when (i) ...

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