Latest Interview Aptitude Question SOLUTION: consider the sequence 1,-2,3,-4,5,-6.what is the average of the first 200 terms in the sequnce?

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(#M40039359) INTERVIEW Category question maths Keep an EYE

consider the sequence 1,-2,3,-4,5,-6.what is the average of the first 200 terms in the sequnce?

Asked In Interview shweta singh (9 years ago)

Unsolved Read Solution (4)

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Habibullah Siddiqui  (9 years ago)

ans -0.5
we can rewrite it as (1+3+5+.....+199)-(2+4+6+....+200)
sum of first n odd natural numbers s=1+3+5+....+(2n-1)=n^2
sum of first n even natural numbers s=2+4+6+....+2n=n^2+n
so acc to above sequence n^2=10000 for odd
and n^2+n=100100 for even
b/c both have 100 terms
hence total sum=10000-100100=-100
aveg=(total sum)/(total no.)
(-100/200)=-0.5

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durga prasad  (9 years ago)

(-1/2)
1-2+3-4+5-6+.......+199-200
-1-1-1-1-1.....-1=-100
-100/2= -1/2

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Snehasis Panda  (8 years ago)

Sum of all odd numbers from 1 to 100 (50 odd numbers) =2500
Sum of all even no from 1 to 100(50 even numbers) =2550
As it is given first 200 terms then,
Ans is ((2500*2)-(2550*2))/200=-0.5

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suresh  (9 years ago)

ans:0.5
(1-2+3-4+5......199-200)/200==0.5

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