A new species of tropical tree has been discovered that doubles its height every year until it reaches its maximum height after 10 years.

**How many years will it take the tree to reach half its height?**

#### Solution

We know that every year it doubles its height so that one year before the 10 in which the tree grows it will be half the height, **this is 9 years**.

By the way, if you look closely you will see that the tree looks like a dancing dancer.