Latest CAT Aptitude Question SOLUTION: consider the sequence of numbers a1,a2,a3....to infinity where a1=81.33 and a2=-19 and aj=(aj-1)-(aj-2).what is the sum of first 6002 terms of this sequence

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consider the sequence of numbers a1,a2,a3....to infinity where a1=81.33 and a2=-19 and aj=(aj-1)-(aj-2).what is the sum of first 6002 terms of this sequence

Asked In CAT prashanthi (11 years ago)

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Huzefa Chikhly  (11 years ago)

x,y,y-x,-x,-y,x-y,x,y....
x=81.33 y= -19
after 6 term it will repeat same sequence
sum of 1st 6 term is 0
so sum of 6002 term is = sum of (6002 mod 6) term= sum of 2 term= 81.33-19=62.33

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Bodavula Krishna Teja  (11 years ago)

clearly the given sequence is in AP.
so sum of n terms of an ap is,
Sn=n/2*{2a+(n-1)d)
=(6002)/2*{2(81.33)+(6001*(-100.33))}
=-1806354927.67

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M.Sathveek  (3 years ago)

If we check for the first 6 terms we get it as a1=81.33, a2=-19, a3=-100.33, a4=-81.33, a5=19, a6=100.33,After this the terms keep on repeating. We have 6 terms difference so till 6000 the terms cancel each other and we get as zero the extra 2 terms (6001 and 6002)will be 81.33 and -19
The sum of the two numbers is 62.33

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