Passage Summary: Merchants in medieval Spain specifically asked to be paid in Senegalese gold coins, even though other coins existed that contained a higher percentage of gold.

Reasoning: Senegalese gold coins were 92 percent pure and easily identifiable by that specific content, whereas other coins could be much purer but required refining.

Analysis: The paradox here is why a merchant would prefer a coin with 92 percent purity over one that is 'much purer.' In a world without modern banking, the ability to verify value is often more important than the theoretical value itself. The stimulus notes that Senegalese coins 'can be recognized because they have that gold content,' suggesting a level of predictability. Look for an answer that explains how the ease of identifying these specific coins outweighed the benefit of the higher gold content found in refined coins, perhaps due to the difficulty of testing purity during a transaction.