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![[Post New]](/templates/default/images/icon_minipost_new.gif) 9 Sep 2008 11:59:13 IST
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the ratio of the sum of n terms of two a.p.'s is (7n+1):(4n+27) the ratio of the mth terms
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9 Sep 2008 13:14:47 IST
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u r dropping...n this is ur Q. ???...relli strange!
its a X level Q.
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9 Sep 2008 13:29:58 IST
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Let the sum for both AP's be :
(n/2){2(4) + (n-1)(7)} and (n/2){2(31/2) + (n-1)(4)}
Both of them are expressed in the form of (n/2)(2a + (n-1)d)
so their mth terms are 4 + (m-1)7 and 31/2 + (m-1)4
7m-3 and 4m + 23/2
so their ratio = (7m-3) / (4m + 23/2) = (14m - 6) / (8m + 23)
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Bipin Kumar Dubey
Chemical Dept.
IIT Kharagpur
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9 Sep 2008 14:08:52 IST
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ALREADY I SEND
SIMPLEST METHOD
SIXTH SEPTEMBER.
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9 Sep 2008 15:20:27 IST
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simplest trick............
write the problem in equation form...
n/2[2a+(n-1)d]/n/2[2A+(n-1)D] = 7n+1/4n+27....
now everywhere replace n by 2m-1....and u'll get the answer.......
14m-6/8m+23
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