In a Lake, there is a patch of lily pads. Every day, the patch doubles in size. It takes 34 days for the patch to cover the entire lake, how many days would it take the patch to cover half of the lake?
Choices:
A) 33
B) 2 ^ 4 * 3
C) 24
D) 38
E) 47

Rationale: "working backward from the day it ' s covered : day 34 : fully covered day 33 : half covered so 33 days answer : a"
Answer: A