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 half of dish?

29 days

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To find out how long it took for the bacteria to fill one half of the dish, we need to determine on which day the bacteria filled the entire dish.

We know that the size of the bacteria doubles each day. So, if it takes 30 days to fill the dish completely, on day 29, the dish would be half-full because the bacteria would double in size one more time on the 30th day.

Therefore, it took the bacteria 29 days to fill half of the dish.