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

• Placement Papers
• /
• TCS
• /
• Numerical Ability
• /
• Number System

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

(#M40111106) TCS Numerical Ability question numerical Keep an EYE

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

Asked In TCS S B HARISH (9 years ago)

Unsolved Read Solution (17)

Is this Puzzle helpful?   (13)   (3) Submit Your Solution Number System

Read Solution (17) :

Surit Datta  (9 years ago)

here if we add two consecutive numbers then we get -1
and then the average would like -1/2
so for 200 terms average will be -100/200
which is -0.5

Is this solution Helpfull? Yes (35) | No   

anusha  (9 years ago)

1-2=-1
3-4=-1
5-6=-1
...........for 6 numbers we get 3*-1
like that for 200 nos we get 100*-1
then -0.5

Is this solution Helpfull? Yes (5) | No   

Rajneeshk  (9 years ago)

find out even or odd no. by this eqen. : = n/2(a+l)
= 1,3,5,7..... = total n=100
= -2,-4,...... = total n=100
So, 100/2(1+199) = 10,000
and 100/2(-2+(-200)) = -10,100
= (10,100 - 10,000)/200
= -0.5

Is this solution Helpfull? Yes (4) | No (1)  

phani krishna  (9 years ago)

-0.5
consider the first two numbers, their sum is -1. there will be 100 such pairs as 200 terms are considered.
so total sum will be -100. average=-100/200=-0.5

Is this solution Helpfull? Yes (3) | No (1)  

Sourabh Prasad  (9 years ago)

1-2=-1
2-3=-1
.
.
..
so there are 100 such pairs whose sum is -1

Therfore, (-1*100)/200
=-100/200
= -1

Is this solution Helpfull? Yes (1) | No (8)  

kumari priyanka  (9 years ago)

1+(-2)=-1
3+(-4)=-1
5+(-6)=-1
total no of such pairs will be 100
and each pair will give -1 result
so adding -1,100 times will result in -100.
so answer is= -100

Is this solution Helpfull? Yes (1) | No (4)  

Shivaraj  (9 years ago)

we have one formula for find sum of 1+3+5+.................
S=(n/2)[2a+(n-1)d]
here
n is how many terms are there in series
a is first term of this series
d is diff between two numbers

first we find out 1+3+5+7 series
S=(100/2)[2*1+(100-1)2]
50*(2+198)
=10000
then 2+4+6+8+.........
s=(100/2)[2*2+99*2]
50*202
=10100
That is in negetive series -10100
next 10000-10100
we get -100
then average is -100/200
we get -0.5
ans is -0.5

Is this solution Helpfull? Yes (1) | No   

rajkumar mukherjee  (9 years ago)

(1+3+5+............+(2*100-1))-(2+4+6+...............+2*100)=100*100-(100*100+100)=-100;
so avg.=-100/200(total terms)=-.5

Is this solution Helpfull? Yes | No (1)  

kajal samal  (9 years ago)

n(n+1)/2
20100

Is this solution Helpfull? Yes | No (3)  

logesh  (9 years ago)

ans:0.5
(1-2+3-3+5-6....200)/200=100/200=0.5

Is this solution Helpfull? Yes | No (3)  

Ganesh A  (9 years ago)

Start pairing of 2numbs then we will get 100 pairs avg of each pair will be -0.5 fr ex avg of 1&-2 is -05
Then fr 100 pairs =(100*(-.5))/100 = -0.5

Is this solution Helpfull? Yes | No (1)  

logesh  (9 years ago)

ans:0.5
(1-2+3-3+5-6....200)/200=-100/200=-0.5

Is this solution Helpfull? Yes | No (1)  

priyanka  (9 years ago)

answer is -0.5

Is this solution Helpfull? Yes | No (2)  

shashank  (9 years ago)

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

Is this solution Helpfull? Yes | No (2)  

SAHELI BISHNU  (9 years ago)

{ (1+3+5+7....199) - (2+4+6+....200) } / 200 = 100/2(2*1+(100-1)2) - 100/2(2*2+(100-1)2)
= 1/2

Is this solution Helpfull? Yes | No (1)  

Rajkumar  (9 years ago)

Ans: 0.5
-

Is this solution Helpfull? Yes | No (1)  

p gayathri  (9 years ago)

sum of odd numbers=n^2 i.e 1 to 199 -> 100 numbers=(100)^2
sum of even numbers=n(n+1) i.e 2 to 200 -> 100 numbers=100*101


(10000-10100)/200=-0.5

Is this solution Helpfull? Yes | No (1)  

Please Login to Read Solution.