Question

If the middle term of the $A.P$ is $300$ then the sum of its first $51$ terms is

• A. 15300
• B. 14800
• C. 16500
• D. 14300

Answer 1

Answer: (A)

mid term is $T_{26}=300$
$T_1=300-25d;T_{51}=300+25d$
$S=\frac{51}{2}[300-25d+300+25d]$
$\frac{51}{2}[600]=15,300$