WBCS Mains 2020 Official Paper-VI

Ranjan sold his bag to Joydip at a gain of $8\%$ and Joydip sold it to Raju at a gain of $10\%$. If Raju paid $\text{Rs. }297$ for it, the price paid by Ranjan is:

If

then $x$ equals:

While preparing a mixture of tea, $5\%$ of the tea is lost. In what ratio should a trader mix two kinds of tea costing $\text{Rs. }600/\text{kg}$ and $\text{Rs. }450/\text{kg}$ respectively so that he might gain $25\%$ by selling the mixed tea at $\text{Rs. }625/\text{kg}$?

If $u_i=\frac{x_i-25}{10}$, $\sum f_i{u}_i=20$, and $\sum f_i=100$, then find the value of the mean $\bar{x}$.

The lateral surface area of a right circular cone is three times the volume of that cone. If the height and the radius of the cone are $h\text{units}$ and $r\text{units}$ respectively, then $\frac{1}{h^2}+\frac{1}{r^2}$ is equal to: