$1200$ boys and $650$ girls appeared in an examination. If $70 \%$ of boys and $40 \%$ of girls failed,find the approximate percentage of passed students.

If the numerator of a fraction is increased by $150 \%$ and the denominator of the fraction is increased by $300 \%$,the resultant fraction is $\frac{5}{18}$. What is the original fraction?

In an examination,$70 \%$ of the candidates passed in English,$80 \%$ passed in Mathematics,and $10 \%$ failed in both subjects. If $144$ candidates passed in both,the total number of candidates was:

$A$ bag contains $600$ coins of $25$ paise and $1200$ coins of $50$ paise. If $12 \%$ of $25$ paise coins and $24 \%$ of $50$ paise coins are removed,the percentage of money removed from the bag is nearly: (in $\%$)

The population of Delhi increases by $10 \%$ every year. If the current population of Delhi is $1,331,000$,what was its population $3$ years ago?

There is a ratio of $5:4$ between two numbers. If $40\%$ of the first number is $12$,then what would be $50\%$ of the second number?