Lily Pads 3
A single lily pad sits in an empty pond. Each day, the lily pad doubles in size. It is known that it would take 10 days for the single lily pad to cover the entire pond. If instead you start with 8 lily pads on the first day, how many days will it take for the surface of the pond to be covered?
Answer
The 8 lily pads can be thought of as a single lily pad that is already three days old since $2^3 = 8$. Thus, it will take 10 - 3 = 7 days for the surface of the pond to be covered.