The marks scored by Mohan in two tests were $62$ and $48$. Find the minimum marks he should score in the third test to have an average of at least $60$ marks.

The solution set of the inequation $\sqrt{x^2+x-2} > (1-x)$ is

The marks obtained by a student of Class $XI$ in first and second terminal examination are $62$ and $48$,respectively. Find the minimum marks he should get in the annual examination to have an average of at least $60$ marks.

The cost and revenue functions of a product are given by $C(x) = 20x + 4000$ and $R(x) = 60x + 2000$ respectively,where $x$ is the number of items produced and sold. The value of $x$ to earn profit is

$A$ container is filled with $1120 \text{ litres}$ of a solution containing $40 \%$ acid. How many litres of acid must be added so that the resulting mixture contains more than $40 \%$ but less than $50 \%$ water?

Solve the following system of inequalities: $\frac{2x+1}{7x-1} > 5$ and $\frac{x+7}{x-8} > 2$.