Subject: General Aptitude · Chapter: Ratio and Proportion · Exam: · Marks: · Difficulty:
The ratio of land to water for the whole earth is 1 : 2 and 2 : 3 in the northern hemisphere. The ratio of land to water in the southern hemisphere is
(a)1 : 3
(b)1 : 4
(c)4 : 7
(d)4 : 11
Answer
Answer (as printed): D
Explanation
Let the area of earth be $x$. Then, area of land on earth $=\frac{x}{3}$; area of water on earth $=\frac{2 x}{3}$. Area of Northern Hemisphere $=\frac{x}{2}$. Area of land in Northern Hemisphere $=\left(\frac{x}{2} \times \frac{2}{5}\right)=\frac{x}{5}$. Area of water in Northern Hemisphere $\left(\frac{x}{2} \times \frac{3}{5}\right)=\frac{3 x}{10}$. Area of land in Southern Hemisphere $=\left(\frac{x}{3}-\frac{x}{5}\right)=\frac{2 x}{15}$. Area of water in Southern Hemisphere $=\left(\frac{2 x}{3}-\frac{3 x}{10}\right)=\frac{11 x}{30}$. $$\text { ∴ } \text { Required ratio }=\frac{2 x}{15}: \frac{11 x}{30}=4: 11 .$$
Explanation as extracted from the printed page; notation may be imperfect.