Question

If $n^{th}$ term of AP is $t_n=4n+1$. Find mean of first $10$ terms.

• A. $85$
• B. $95$
• C. $23$
• D. $7.5$

Answer 1

The correct option is C $23$

Given:

$t_n=4n+1$

$\therefore A.M.=\frac{{\sum }_{n=1}^{10}4n+1}{n}$

$=\frac{2n(n+1)+n}{n}$

$=2n+3$

$=2\times 10+3$

$=23$