In a lake, there is a patch of lily pads. Every day, the patch doubles in size. If it takes 48 days for the patch to cover the entire lake, how long would it take for the patch to cover half the lake?
Answer: The patch doubles in size every day and so on the 47th day the patch will be half the size it is on the 48th day.
This riddle appears in the following downloadable PDF files: