Question

The sum of `n' terms of a finite AP is $\frac{13}{2}$ times the sum of its first and last terms. Which term would be the middle term in this AP?

• A. 3rd term
• B. 5th term
• C. 7th term
• D. 9th term

Answer 1

The correct option is C 7th term

For a finite AP having first term as a and last term as l, the formula for the sum of n terms would become $\frac{n}{2}(a+l)=\frac{n}{2}(firstterm+lastterm)$.

Now, in the question it is given that the sum of n terms is $\frac{13}{2}$ times the sum of its first and last terms, which means,
n = 13
Since, the AP has 13 terms.
So, the 7th term is the middle term.