The ratio of the income to the expenditure of a family is $10:7$. If the family's expenses are $Rs. 10500$,then the savings of the family is (in $Rs.$):

Two numbers are respectively $20 \%$ and $50 \%$ more than a third number. The ratio of the two numbers is

In a mixture of $60 \ L$,the ratio of milk and water is $2:1$. What quantity of water (in $L$) should be added so that the ratio becomes $1:3$?

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?

The third proportional to $0.8$ and $0.2$ is

$A, B, C$ and $D$ purchase a gift worth $Rs. 60$. $A$ pays $\frac{1}{2}$ of what others are paying,$B$ pays $\frac{1}{3}$ of what others are paying,and $C$ pays $\frac{1}{4}$ of what others are paying. What is the amount paid by $D$?