What is the sum of the first 50 common numbers between the series 15,19,23....... and 14,19,24.........?
A) 25550
B) 24540
C) 24450
D) 25450
E) 25540
The given series are increasing by 4 and 5 respectively..
so the LCM=20
Hence they will have common numbers every 20...so common numbers will be like 19, 39, 59...
The common numbers is also an arithmetic series starting with 19 and with a difference of 20 between consecutive numbers....
therefore a=19
d=20
n=50
sum of arithmatic series
s = n/2(a+(n-1)*d)
= 25(19+49*20)
= 25450