Riddle A: A snail fell into a hole 30 feet deep. It tries to climb out, but can only climb up 3 feet in a day. At night, while sleeping, it slips back down 2 feet. How many days does it take the snail to get out of the hole?
Riddle B: A school science project involves placing a bacteria cell into a jar. The bacteria reproduces at a rate such that the total population doubles every day. (so on the second day there are 2, the third day there are 4, etc). If it takes 30 days before the jar is completely full, on which day was the jar half full?