Water Lilies Puzzle

In the beginning, the pond had only one water lily.  The next day there were two lilies.  Each day, the area the lilies covered doubled in size.

On the last day of August the lilies covered the pond completely.

1. On which day, did the lilies cover at least half of the pond?
2. On which day, did the lilies cover at least a quarter of the the pond?

3. If in the beginning there were two water lilies, on which day did the lilies cover the pond completely?

How many days in August?

Solutions