Question

The sum of $3^{rd}$ and ${15}^{th}$ elements of an arithmetic progression is equal to the sum of $6^{th}$, ${11}^{th}$ and ${13}^{th}$ elements of the same progression. Then which elements of the series should necessarily be equal to zero?

• A. $1^{st}$
• B. $9^{th}$
• C. ${12}^{th}$
• D. None of the above

Answer 1

The correct option is C ${12}^{th}$