In a Lake, there is a patch of lily pads. Every day, the patch doubles in size. It takes 50 days for the patch to cover the entire lake, how many days would it take the patch to cover half of the lake?  Pick:
A) 36	B) 2 ^ 4 * 3	C) 24	D) 49	E) 47

Rationale: "working backward from the day it ' s covered : day 50 : fully covered day 49 : half covered so 49 days answer : d"
Answer: D