If you change a four-lane highway into a six-lane highway and back again, by how much do you increase its capacity? Reckoning the Odds
Chris McManus, 17 October 2002
The sales of a company fall by 50 per cent between January and May. Between May and September sales increase by 60 per cent. Is the company in better shape in September than it was in January? Down by 50 per cent and up by 60 per cent sounds like an overall 10 per cent gain. But it’s not.