WBCS Mains 2020 Official Paper-VI

The difference between simple interest and compound interest on a sum for $3$ years at $10\%$ when the interest is compounded annually is $\text{Rs. }155$. Then the principal value is

The current population of a town is $120000$. If the population increases by $10\%$ every year, then the population of the town after three years will be

If ${\left(x+\frac{1}{x}\right)}^2=3$, then the value of $x^{2020}+x^{2021}+x^{2022}+x^{2014}+x^{2015}+x^{2016}+1$ is

If $3\sin \alpha +5\cos \alpha =5$, then the value of $(3\cos \alpha -5\sin \alpha {)}^2$ is equal to

Out of $15$ cows, one worth $\text{Rs. }1800$ was removed and a horse was taken in. If their average price is thereby increased by $\text{Rs. }300$, then the price of the horse is