The ratio of land to water on the Earth is 1 : 2. In the northern hemisphere the ratio is 2 : 3. What is the ratio of land to water in the southern hemisphere?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 4 : 11
The two hemispheres are equal halves of the Earth's surface, so the land of the southern half is the whole land minus the land of the northern half.
Take each hemisphere as 1 unit of area; the Earth is 2 units
Land on the Earth \(\displaystyle =\frac{1}{3}\times2=\frac{2}{3}\)
Land in the northern hemisphere \(\displaystyle =\frac{2}{5}\times1=\frac{2}{5}\)
Land in the southern hemisphere \(\displaystyle =\frac{2}{3}-\frac{2}{5}=\frac{4}{15}\)
Water in the southern hemisphere \(\displaystyle =1-\frac{4}{15}=\frac{11}{15}\)
The ratio in the southern hemisphere is 4 : 11.