Riddle me this

United States
December 16, 2006 11:10pm CST
A water lily growing in a circular pond doubles in size every day. It takes thirty days to cover the whole pond. How long does it take to cover half the pond?
1 response
@mythmoh (3984)
• United States
17 Dec 06
as it takes 30 days to cover the whole pond,sure for half it will take less than 30 days.As it is growing in ddouble the size it will take 29 days.next day will be full.
• United States
20 Dec 06
Correct.