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If ""^(10)P(r) = 720, find r....

If `""^(10)P_(r)` = 720, find r.

A

4

B

2

C

3

D

1

Text Solution

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The correct Answer is:
C
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Explore conceptually related problems

(i) If ""^(15)P_(r)=2730, find the value of r. (ii) If ""^(10)P_(r)=5040, find the value of r.

10p_(r)=720

If ""^(15)P_(r-1): ""^(16)P_(r-2)=3:4 , find r.

If ^(10)P_(r)=5040, find the value of r

If .^(n)P_(r) = 720 and .^(n)C_(r) = 120 , then find r. = (5 xx 4 xx 3)/(3 xx 2 xx1) xx (4xx 3 xx 2)/(3 xx 2xx1) = 10 xx 4 = 40 .

If ""^(22)P_(r+1):""^(20)P_(r+2)=11:52, find r.

(i) If ""^(5)P_(r)=2xx""^(6)P_(r-1) , find r. (ii) If ""^(20)P_(r)=13xx""^(20)P_(r-1) , find r. (iii) If ""^(11)P_(r)=""^(12)P_(r-1) , find r.

(a) If .^(22)P_(r+1):^(20)P_(r+2)=11 : 52 , find r. (b) If .^(56)P_(r+6):^(54)P_(r+3)=30800: 1 , find r.

DISHA PUBLICATION-PERMUTATIONS AND COMBINATIONS-PRACTICE EXERCISES ( FOUNDATION LEVEL)
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