The value of which of the following fractions is less than $20\%$

In an examination, Mohit obtained $540$ marks out of $600$. What percentage of marks did he get?

Out of every $50$ vehicles passing a certain spot $9$ were buses. What percentage was this?

Nikhil bought $5400$ books in a month and sold $4050$ books. What per cent of books he could not sell?

A Maruti car costing $₹ 2,50,000$ dropped $23\%$ in value of the first year. How much was it worth at the end of the year?

A $4$ metre elastic band is increased by $10\%$. Find its new length.

The length of a wire is decreased by $12\frac{1}{2}\%$. What is the new length if it was $150$ metres?

In a certain year, the population of a state is $8$ crore. If it increases by $2\%$ every year, what will be its population after one year?