Question

The sum of $2,7,12,..............$ to $10$ terms is :

• A. $240$
• B. $248$
• C. $245$
• D. $250$

Answer 1

The correct option is C $245$

Given series is: $2+7+12+........$ to $10$ terms
Here, $a=2,d=7-2=5,n=10$
$\Rightarrow S_n=\frac{n}{2}\{2a+(n-1)d\}$
$\Rightarrow S_{10}=\frac{10}{2}\{4+45\}$

$=5\times 49$

$=245$