Solution: Cab Conundrum
To explain this paradox, you need only to add up the amounts. The fare was $25, the tip was two dollars, and each man kept one dollar. This adds up to $30. The error in reasoning is caused by the sentence that says, “Each man has now spent nine dollars and the driver has two dollars for a total of $29.” Actually the first part of this sentence is correct-each man does spend nine dollars, since the total cost of the cab ride is $27 (the $25 fare and the $2 tip). The error comes in the second part of the sentence. What needs to be added to this 27 dollars is the three dollars that the men keep, not the two dollar tip-the tip was accounted for in the cost of the ride.