Magical Lily Pads

by | Brain Teasers

In ancient Egypt, there were magical lily ponds. On these ponds, each flower doubled overnight. For example, if a pond had one flower on a certain day, the next day there would be two flowers (both the same size as the original flower).

On March 1, a single flower was placed on an empty magical pond. On the last day of the month, March 31, the pond’s entire surface was 100% perfectly filled with flowers. What was the first day on which the pond’s surface was at least 30% covered with flowers?

Scroll to the bottom to see the answer!


Answer:

The answer is March 30. If the pond was 100% full on March 31, then it was 50% full on March 30, and 25% full on March 29. So, the first day it was at least 30% full was March 30.