Question

The first term of a G.P is $7,$ the last term is $567$ and sum of terms is $847$. Find the common ratio of the G.P.

• A. $3$
• B. $2$
• C. $4$
• D. $6$

Answer 1

The correct option is A $3$

Given $a=7$ the first term
$t_n=a{r}^{n-1}=567$

$\Rightarrow 7r^n=567r$

Also $S_n=\frac{a(r^n-1)}{r-1}=\frac{7(r^n-1)}{r-1}$

$847=\frac{567r-7}{r-1}$

$\therefore r=3$