The sum of all natural numbers from 75 to 97 is :

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The sum of all natural numbers from 75 to 97 is :

1. 1598
2. 1798
3. 1958
4. 1978

Correct Option: D

Series of all natural numbers from 75 to 97 is in A.P. whose first term, a = 75, last term, l = 97
If number of terms be n, then
a_n = a + ( n – 1 )d
⇒ 97 = 75 + ( n – 1 )
⇒ n = 97 – 74 = 23

S_n =	n	(a + 1)
	2

S₂₃ =	23	(75 + 97)
	2

S₂₃ =	23	× 172 = 1978
	2