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What belongs in each mystery box?

Every mystery box holds the same value. Make the two sides balance.

5 × ? + 666Equal values make a level balance.

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Our worldAges 16-18Human geography
Question 1 of 4
Per-capita water consumption

Population density is 5800 people/km² in the city centre and falls by 125 people/km² for each kilometre outward. What is the density 4 km from the centre?

Divide total daily community water use by population to find per-capita consumption in litres.

5800 · 125 · 4 km · Per-capita water consumption
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Our world category

Featured, challenges & worksheets in Our world

CartographyFeatured

Longitude & time-zone offsets

Use Earth’s 15°-per-hour rotation rate to calculate local standard time from longitude offsets.

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Human geographyFeatured

GDP per capita & output

Divide national or regional Gross Domestic Product (GDP) by population to find GDP per capita.

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SustainabilityFeatured

Clean energy & avoided emissions

Calculate avoided carbon dioxide emissions from clean electricity generation over time.

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