Latest TCS Aptitude Question SOLUTION: if S= 1/7 + 3/(7^2) + 7/(7^3) + 13/(7^4)+ ........ then S = 1)25/111 2)25/108 3)25/216 4)1/4

• Placement Papers
• /
• TCS
• /
• Numerical Ability
• /
• Data Interpretation

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

(#M40032176) TCS Numerical Ability question number Keep an EYE

if S= 1/7 + 3/(7^2) + 7/(7^3) + 13/(7^4)+ ........ then S =

1)25/111
2)25/108
3)25/216
4)1/4

Asked In TCS saranya sankar (10 years ago)

Unsolved Read Solution (4)

Is this Puzzle helpful?   (13)   (2) Submit Your Solution Data Interpretation

Read Solution (4) :

mohan lal garg  (10 years ago)

S= 1/7 + 3/(7^2) + 7/(7^3) + 13/(7^4)+21/7^5 ....
s-s/7=1/7 + 2/(7^2) + 4/(7^3) + 6/(7^4)+8/7^5 ....=6s/7
6s/7-6s/49=1/7 + 1/(7^2) + 2/(7^3) + 2/(7^4)+ ....
36s/49=8/49+(2/243)/(1-1/7)(infinite series formula)
36s/49=8/49+2/49*6=50/49*6
s=50/216
s=25/108
option 2 is right ans ......

Is this solution Helpfull? Yes (7) | No   

mohan lal garg  (10 years ago)

S= 1/7 + 3/(7^2) + 7/(7^3) + 13/(7^4)+21/7^5 ....
s-s/7=1/7 + 2/(7^2) + 4/(7^3) + 6/(7^4)+8/7^5 ....=6s/7
6s/7-s/7=1/7 + 1/(7^2) + 2/(7^3) + 2/(7^4)+ ....
5s/7=8/49+(2/243)/(1-1/7)(infinite series formula)
5s/7=8/49+2/49=10/49
s=2/7 ans......
none of these

Is this solution Helpfull? Yes (3) | No   

Dheeraj   (9 years ago)

S= 1/7 + 3/(7^2) + 7/(7^3) + 13/(7^4)+ ........ eq 1
s-1/7 = 3/(7^2) + 7/(7^3) + 13/(7^4)+ ........
7s-1 = 3/7 + 7/(7^2) + 13/(7^3)+ ........ eq2
eq2-eq1:
6s-1 = 2/7+4/(7^2)+6/(7^3)+8/(7^4)+........
3s-1/2= 1/7 + 2/(7^2)+3/(7^3)+4/(7^4)+........ Eq3
3s-1/2-1/7 = 2/(7^2)+3/(7^3)+4/(7^4)+........
21s-9/2 = 2/(7)+3/(7^2)+4/(7^3)+........ Eq4
Eq4-Eq3
18s-4 = (1/7)/(1-1/7)
18s -4 = 1/6
18s = 1/6 + 4
18s = 25/4
s = 25/108

so ans is option B

Is this solution Helpfull? Yes (3) | No   

mohan lal garg  (10 years ago)

S= 1/7 + 3/(7^2) + 7/(7^3) + 13/(7^4)+21/7^5 ....
s-s/7=1/7 + 2/(7^2) + 4/(7^3) + 6/(7^4)+8/7^5 ....=6s/7
6s/7-6s/49=1/7 + 1/(7^2) + 2/(7^3) + 2/(7^4)+ ....
36s/49=8/49+(2/243)/(1-1/7)(infinite series formula)
36s/49=8/49+2/49*6=50/49*6
s=50/216
s=25/108
option 2 is right ans .........
s=2/7 ans......
none of these

Is this solution Helpfull? Yes | No   

Please Login to Read Solution.