Nobel award winning physicist and his limo driver

A Nobel award winning physicist, who was afraid of flying, was on speaking tour of the nation's top colleges. He travelled by limousine to each destination to give his speech.
After two dozen engagements, the physicist and the limousine driver were having dinner before the next speech. The limousine driver commented that he'd heard the speech enough times, and that even though he didn't understand it, he felt as if he could deliver it word-for-word. So the physicist agreed to trade places and let him give the speech, and the physicist would sit in the back and wear the limousine driver's uniform.
After giving the speech flawlessly, the limousine driver opened the floor for questions from the students (typically there were none). However, at this particular University there was a rather egotistical student who thought he was smart enough to compete mentally with the Nobel physicist. The question took 5 minutes to get out and would require a rather lengthy explanation and some complex calculus to answer.
Without batting an eye, the limousine driver responded to the young student by saying, "The answer to that question is so easy, I'll let my limousine driver, seated in the back, respond."