The earth's surface is covered either by land or by water. The proportion covered by land is $\frac{3}{5}$ of that covered by water. What fraction of the entire surface of the earth is land?

What is the combined ratio of 3:2, 7:4 and 6:5?

In a mixture of $165$ litres, the ratio of liquids $X$ and $Y$ is $6:5$. If $5$ litres of liquid $Y$ is added in the mixture, then what is the ratio of $X$ and $Y$ in the new mixture ?

If we divide 184 kg in the ratio 2 : 3 : 3, the relevant measures in kg are:

(A) 26, 79 and 79 

(B) 6, 89 and 89 

(C) 46, 79 and 79 

(D) 46, 69 and 69 

What is the $4th$ proportional of $3, 8, 12$ ? 

1. $36$

2. $26$

3. $32$

4. $16$

A box contains one rupee, fifty paisa and twenty five paisa coins. The total number of coins are $378$. The ratio of values of the above coins is $13:11:7$. The number of twenty five paise coins was:

In water, The ratio of the mass of hydrogen to the mass of oxygen is always _____.