The present ages of three persons are in the ratio $4: 7: 9$. Eight years ago,the sum of their ages was $56$. Find their present ages (in $years$).

$x$ varies inversely as the square of $y$. Given that $y=2$ when $x=1$. The value of $x$ when $y=6$ will be equal to:

$15$ litres of mixture contains $20 \%$ alcohol and the rest water. If $3$ litres of water be mixed with it,the percentage of alcohol in the new mixture would be:

In a college,$150$ students of $MBA$ are enrolled. The ratio of boys to girls is $7:8$. There are three disciplines in the college: Marketing,$HR$,and Finance. In the Marketing discipline,there are $50\%$ girls of their total number and the boys are $40\%$ of their total number. In the $HR$ discipline,girls are $30\%$ of their total number while boys are $30\%$ of their total number. The Finance discipline has girls $20\%$ of their total number and the boys are $30\%$ of their total number. $7$ boys and $9$ girls are in $HR$ and Marketing both. $6$ boys and $7$ girls are in $HR$ and Finance both. $5$ boys and $8$ girls are in Marketing and Finance both. $2$ boys and $3$ girls are enrolled in all the three disciplines. By what percent is the number of boys in the Marketing discipline more than the number of girls in the $HR$ discipline?

Find the third proportional to the numbers $4$ and $42$.

$A$ sum of money is to be distributed among $A, B, C$ and $D$ in the proportion of $5: 2: 4: 3$. If $C$ gets ₹ $1000$ more than $D$,what is $B$'s share (in ₹)?