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For Richer for Poorer

Age 14 to 16 Challenge Level:

In the rich country of Emerald, the average income is £20,000.
In the poorer, neighbouring country of Flint, the average income is £16,000.
Charlie lives in Emerald and earns £18,000 a year.
He moves to Flint and says "I've made both countries richer!"
What does he mean?

Charlie thinks that the average income in both countries has increased.
Can you convince yourself that Charlie is right?

What other effects can moves between countries have on the average incomes?

Describe what is required for moves to:
  • increase the average incomes in both countries
  • decrease the average incomes in both countries
  • increase one whilst decreasing the other

Would it be possible for someone to move from Emerald to Flint and reduce the average income in Emerald and double the average income in Flint?