Arithmetichard · Past Paper

The ratio of land to water for the whole earth is 1:2 and in the northern hemisphere it is 2:3. What is the ratio of land to water in the southern hemisphere?

A4:11
B11:4
C5:7
D7:5

✓ Correct Answer: A4:11

Total Land = 1/3, Water = 2/3. Northern Hemisphere is 1/2 of earth. Land there = (2/5)*(1/2) = 1/5. Southern Land = 1/3 - 1/5 = 2/15. Southern Water = 1/2 - 2/15 = (15-4)/30... wait. Let's use total 30 units: Land 10, Water 20. North (15 units) has Land = 15*(2/5)=6, Water=9. South (15 units) has Land = 10-6=4, Water = 20-9=11. Ratio 4:11.

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