Find the sum of an AP of 40 terms whose first and last terms are 80 and 275.

M4maths Previous Puzzles

02 Nov 2020 Arithmetical Progression

Find the sum of an AP of 40 terms whose first and last terms are 80 and 275.

OPtion

1) 8400
2) 7200
3) 7100
4) 4800
5) 7600
6) 8600
7) 7500
8) 6800
9) 5800
10) None of above

Solution

As given, a1= 80 and a40 = 275
S40 = n / 2 ( a1 + a40 ) = 40/2 ( 80 + 275 )
= 20 x 355 = 7100

Correct Option: 3 Best Solution (3)