Final answer:
The 30% higher cost of Coca-Cola in Japan is an example of the concept of purchasing power parity, which accounts for differences in price levels between countries for similar goods and services.
Step-by-step explanation:
The difference in price you noticed for the Coca-Cola in Japan compared to your country's money can be attributed to purchasing power parity (PPP). The concept of PPP relates to the relative value of two countries' currencies based on the prices of similar goods and services in each country. When economists compare the GDP of different countries, they often use PPP exchange rates to account for differences in price levels, thus making international comparisons more meaningful.
For your scenario where the Coca-Cola costs 30% more in Japan, it's an example of how the exchange rate alone does not always reflect the true cost of goods and services due to varying price levels between countries. PPP takes this into account by equalizing the purchasing power of different currencies by considering the prices of a basket of goods that are internationally traded.