Question

The sum of first ten multiples of 6 lying between 100 and 300 is equal to:

[1 Mark]

• A. 258
• B. 290
• C. 1,290
• D. 2,190

Answer 1

The correct option is C 1,290

Multiples of 6 lying between 100 and 300 are 102, 108, 114,...
102, 108, 114,... are in AP.
First term, a = 102
Common difference, d = 6
Number of terms, n = 10
$S_n=\frac{n}{2}(2a+(n-1\left)d\right)$ $=\frac{10}{2}(2\times 102+(10-1)\times 6)$
$=5\times 258=1,290$