The ratio of land and water on earth is 1: 2. In the northern hemisphere, the ratio is 2: 3. What is the ratio in the southern hemisphere?
Answer & explanation
Correct answer: option 4
Let's assume the total area of the Earth is 300 units.
Since the Earth is divided equally into two halves, each hemisphere has an area of 150 units:
- Northern Hemisphere = 150 units
- Southern Hemisphere = 150 units
The total Earth ratio of land to water is $1:2$ (total of 3 parts).
- Total Land = $\frac{1}{3} \times 300 = 100\text{ units}$
- Total Water = $\frac{2}{3} \times 300 = 200\text{ units}$
The ratio in the Northern Hemisphere is $2:3$ (total of 5 parts) out of its 150-unit area.
- Northern Land = $\frac{2}{5} \times 150 = 60\text{ units}$
- Northern Water = $\frac{3}{5} \times 150 = 90\text{ units}$
Subtract the Northern Hemisphere's amounts from the Earth's totals:
- Southern Land = $\text{Total Land} - \text{Northern Land} = 100 - 60 = 40\text{ units}$
- Southern Water = $\text{Total Water} - \text{Northern Water} = 200 - 90 = 110\text{ units}$
The ratio of land to water in the Southern Hemisphere is $40:110$, which simplifies to 4:11.
Therefore, the correct choice is 04:11.