Latest Infosys Aptitude Question SOLUTION: What is the sum of first 100 terms which are common to both the progressions? 17,21,25,... and 16,21,26,... a)120000 b)100000 c)101111 d)101100 e)130000

• Placement Papers
• /
• Infosys
• /
• Logical Reasoning
• /
• Letter Series

Infosys Question Papers: Infosys Interview Experience(10) INFOSYS Company Profile

(#M40005131) INFOSYS Logical Reasoning question infosys latest puzzle Keep an EYE

What is the sum of first 100 terms which are common to both the progressions? 17,21,25,... and 16,21,26,...
a)120000
b)100000
c)101111
d)101100
e)130000

Asked In Infosys (12 years ago)

Unsolved Read Solution (3)

Is this Puzzle helpful?   (11)   (3) Submit Your Solution Letter Series

Read Solution (3) :

Dr.Dipin Singh  (12 years ago)

terms will be 1+20*1, 1+20*2, ...... 1+20*n where n = 100

sum of first 100 such terms = 1+20*1+ 1+20*2 + ......+ 1+20*n
= 100 +20*(1+2+....+100)= 100+20*101*100/2 = 100+1000*101 = 101100 .... option d)

Is this solution Helpfull? Yes (7) | No   

anant  (5 years ago)

17,21,25,29,33,37,41,45,49,53,57,61....(difference is 4)
16,21,26,31,36,41,46,51,56,61,66,71......(difference is 5)
from above 2 series the common terms are 21,41,61,.......(consider this as new series )
as we can see they are A.P with common difference as 20
by formula
Sn=n/2(2*a+(n-1)d)
a=first term of series, d= difference of terms,Sn= sum of n terms
s100=100/2*(2*21+(100-1)20)
=101100

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

saranya.k  (9 years ago)

explain the ans briefly

Is this solution Helpfull? Yes | No (2)  

Please Login to Read Solution.