The correct answer really depends on what role the candidate is trying to get. An engineering person would come up with the thought process to their estimate.

The correct answer really depends on what role the candidate is trying to get. An engineering person would come up with the thought process to their estimate. A business person might start asking questions about the business needs for trying to fill a 747 with ping pong balls. But someone trying to get an engineering role should think twice before trying to sound smart and replying in an out of line manner.