Latest TCS Aptitude Question SOLUTION: Consider the sequence 1,-2, 3,-4, 5,-6, ….. , what is the average of the first 2000 terms of the sequence?

• Placement Papers
• /
• TCS
• /
• Numerical Ability
• /
• Sequence and Series

TCS Question Papers: TCS Interview Experience(90) TCS Company Profile

(#M40039401) TCS Numerical Ability question Keep an EYE

Consider the sequence 1,-2, 3,-4, 5,-6, ….. , what is the average of the first 2000 terms of the sequence?

Asked In TCS SUDIP ROY (9 years ago)

Unsolved Read Solution (15)

Is this Puzzle helpful?   (2)   (0) Submit Your Solution Sequence and Series

Read Solution (15) :

karthikeyank  (9 years ago)

Ans is -1/2
=-(1+1+1.....upto 1000 trms)/2000
=-1/2

Is this solution Helpfull? Yes (21) | No (1)  

Chandra chur anand  (9 years ago)

(1,3,5,..1999) here n=1000
s1=n/2(2a+(n-1)d)=10000000
(-2,-4,-6...,-2000) here n=1000
s2=-1001000
so avg term= s1+s2/2000term
=-1000/2000
=-1/2 ans.

Is this solution Helpfull? Yes (4) | No   

VIVEK KUMAR GAUTAM  (9 years ago)

ans.=-1/2
-1-1-1....(1000th)/2000

Is this solution Helpfull? Yes (2) | No   

manoj  (9 years ago)

1-2=-1
3-4=-1
.
.
.
.
-1,1000 times
so ans=-1000/2000
=-1/2

Is this solution Helpfull? Yes (2) | No   

karthikeyank  (9 years ago)

@KARTHIKEYAN
TOTAL 2000 TERMS
JUST TAKE IT THE PAIR SEQUENCE EX:(1,-2)
SO 1000 PAIRS IN 2000 TERMS

Is this solution Helpfull? Yes (2) | No (1)  

debayan khanra  (9 years ago)

ans is -1/2..

Is this solution Helpfull? Yes (2) | No   

karthikeyank  (9 years ago)

Ans is -1/2
=-(1+1+1.....upto 100 trms)/200
=-1/2

Is this solution Helpfull? Yes (1) | No   

rashmi chaturvedi  (9 years ago)

1+3+5...1000 terms + -2-4-6..1000 terms
1000/2[(2+(999*2))+2*(999*-2)]
=-998000

Is this solution Helpfull? Yes | No (6)  

karthikeyan  (9 years ago)

pls explain in the ans karthi

Is this solution Helpfull? Yes | No   

swapnil saxena  (9 years ago)

( on comininig 2 term eg((1,-2)(3,-4)...) we get -1 for 2000 term sum would be
-1000) av =(-1000)/2000
=-1/2

Is this solution Helpfull? Yes | No   

Ravinder singh  (9 years ago)

first sequence is 1,3,5...... (1000 terms )
second sequence is -2,-4.-6........ (1000 terms)
use formula to find the sum of series =(n/2)(2a+(n-1)d)
answere = -1/2

Is this solution Helpfull? Yes | No   

Abhinav Kumar  (9 years ago)

@Karthikeyank:
(-1/2) is incorrect.
Average of a series is always positive.
ans is (+1/2)

Is this solution Helpfull? Yes | No (1)  

sandipan  (9 years ago)

sum=500*(2+4)+500*(-4-4)/2000=-.5

Is this solution Helpfull? Yes | No   

roja  (9 years ago)

ans is -0.5

Is this solution Helpfull? Yes | No   

Poonam Pipaliya  (8 years ago)

see guyzz, here 1,-2,3,-4,.....,200
now if we know that what is the answer of first 10 terms then we can calculate the for 200 terms.
here summing first 10 terms
1-2+3-4+5-6+7-8+9-10
=-1-1-1-1-1
=-5
here for 10 terms answer is half 10/2=-5
so that for 200=200/2=-100
and for average total by total numbers=-100/200=-.5

Is this solution Helpfull? Yes | No   

Please Login to Read Solution.