Answer:
If a Dollar is worth $ 0.7809 Euros in New York, and $ 0.7793 Euros in Paris, the way in which foreign exchange traders could obtain an economic profit through this difference would be by buying Euros in Paris, and selling them again in New York. Thus, they would obtain $ 0.016 of profit for each Euro traded in the market, with which, for example, if $ 1,000,000 of Euros were traded, a total profit of $ 16,000 would be obtained. In turn, trading the same amount in both Paris and New York, traders would not make any profit, equating both exchange rates.