When the door of the Chapel of the Mausoleum in Hamilton, Scotland, is slammed shut, the last echo heard by someone standing just inside the door reportedly comes l5s later.
(a) If that echo were due to a single reflection off a wall opposite the door, how far from the door would that wall be?
(b) If, instead, the wall rs 25.7 m away, how many reflections (back and forth) correspond to the last echo?