WBCS Mains 2020 Official Paper-VI

The production of scooters rose to $48400$ from $40000$. If the rate of growth is $10\%$, then the time required is

Two circles with radii $r_1$ and $r_2$ respectively, touch each other externally. Let $R$ be the radius of a circle that touches these two circles as well as their common tangent line. Which of the following relations is true?

Amal invests $\frac{1}{4}$ of his capital at $8\%$ p.a., $\frac{1}{5}$ at $10\%$ p.a., and the remainder at $7\%$ p.a. If his total annual income from interest is $\text{Rs. }628$, then his total capital is

The mean of a frequency distribution is $8.1$. If $\sum f_i{x}_i=132+5k$ and $\sum f_i=20$, then the value of $k$ is

A manufacturer marked an article at $\text{Rs. }120$ and sold it allowing a $15\%$ discount. If his profit was $20\%$, then the prime cost (cost price) of the article is