Question

The sum of first 15 multiples of 8 are :

2 points

(a) 960

(b) 1000

(c) 940

(d) 1060

​

Answer 1

Answer:

The is sum of first 15 multiples is 8 are 960

Answer 2

using Ap

where,a=8,d=8,n=15

using formula of sn

$sn = \frac{n}{2} \times (a + (n - 1)d$

$sn = \frac{15}{2} \times (8 + 14 \times 8)$

$= \frac{15}{2} \times( 8 + 112)$

$\frac{15}{2} \times 120$

$= 15 \times 60$

$= 900$