Lotus Lake
A particular lake has lotuses growing on it. On the first day, there is one lotuses. Each day, the number of lotuses doubles. After 30 days, the lotuses cover half the lake. How long before they also cover the other half of the lake, so the whole lake is full?
Ans: The lotuses filled half the lake in 30 days. The number doubles daily. So on day 31, they fill the lake. Did you get this right?