Passengers using New York's MetroCard system must swipe the card at a rate between 10 and 40 inches per second, or else the card must be re-swiped through the card reader. Re- search shows that actual swipe rates by subway riders are uniformly distributed between 5 and 50 inches per second.
(a) What is the mean swipe rate?
(b) What is the standard deviation of the swipe rate?
(c) What are the quartiles?
(d) What percentage of subway riders must re- swipe the card because they were outside the acceptable range? (Data are from The New York Times, July 18, 2004, p. 23.)