Find a single equivalent increase,if a number is successively increased by $10 \%$,$20 \%$,and $25 \%$. (in $\%$)

An engineering student has to secure $25 \%$ marks to pass. He gets $47$ marks and fails by $43$ marks. What are the maximum marks of the examination?

Rita invested $25 \%$ more than Sunil. Sunil invested $30 \%$ less than Abhinav who invested $Rs. 6000$. What is the respective ratio between the amount that Rita invested and the total amount invested by all of them together?

$A$ boy found the answer for the question "subtract the sum of $\frac{1}{4}$ and $\frac{1}{5}$ from unity and express the answer in decimals" as $0.45$. The percentage of error in his answer was

$4598$ is $95 \%$ of what number?

In an examination,$35 \%$ of the students passed and $455$ failed. How many students appeared for the examination?