SSC GD Constable 2015 · Question 25 of 88
number-system
tn=a+(n-1)d where tn = nth term, a= first term n=no. of terms d= difference between terms Here tn= 97,a=74,d=1 97=74+(n-1)1 ⇒97=73+n ⇒ n=23 Sum of natural numbers between 74 and 97 is n n Sn= 2 [2a+(n-1)d] Here n=23, a=74, d=1 23 Sn= 2 [74+(23-1)1] 23 = 2 × 172= 23 × 86=1978 ∴ Sum of natural numbers between 74 and 97 is 1978
Source: Solved SSC GD 2015 Paper with Solutions — Collegedunia · reliable-secondary
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