Passengers using New York's MetroCard system must swipe the card at a rate between 15 and 31 inches per second, or else the card must be re-swiped through the card reader. Research shows that actual swipe rates by subway riders are uniformly distributed between 2 and 41 inches per second.
a) What is the mean swipe rate? (Round your answer to 2 decimal places.)
b) What is the standard deviation of the swipe rate? (Round your answer to 2 decimal places.)
c) What are the 1st and 3rd quartiles? (Round your answers to 2 decimal places.)
d) What percentage of subway riders must re-swipe the card because they were outside the acceptable range? (Round your answer to 2 decimal places.)