A local government ask for bids to dig a tunnel. The received three offers, two of them were coming from two well known local contractors, and the cheapest from someone called “Smith Bros". The price difference among this latter offer and the former two was so high, that the people studying the proposals decided to call one of the brothers to be sure of the viability of the project.

“Well, we would like to know how, meanwhile two of the first-line contractors are bidding at a price three or four times yours, you are going to be able to build the tunnel for that cheap prize?”

“Well, it is very easy!”, he replied, “while the companies you mentioned before are using a very expensive machinery I will start digging, with a group of people, in one side of the mountain at the same time my brother is doing the same in the other side. When we meet each other you will have the tunnel done.”

“Well, that sounds nice, but what would happened if you did not meet each other?" one of the inquiring people asked.

“No problem!“ he replies, “if that was the case, you will have two tunnels for the price of only one!”