It takes 30 days to fill a laboratory dish with bacteria. If the size of the bacteria doubles each day, how long did it take for the bacteria to fill one eighth of the dish? Select the correct option.
A) 10 days B) 15 days C) 27 days D) 28 days E) 29 days
The bacteria doubles each day, so after 29 days, the dish was half full.   After 28 days, the dish was one quarter full.   After 27 days, the dish was one eighth full.   The answer is 27 days.
<result>C</result>
It takes 30 days to fill a laboratory dish with bacteria. If the size of the bacteria doubles each day, how long did it take for the bacteria to fill one eighth of the dish?