How tall is the tree?

Anne is standing next to a tree that casts a shadow of 21 feet long. Anne is 4 feet tall and her shadow is 3 feet long. How tall is the tree?

* This problem involves ratio and proportions

The height of something and its shadow will be directly proportional, so we can use a ratio to find out how tall the tree is. 

Let us define the height of the tree as h.

In this case, we know that the ratio between Anne's height and Anne's shadow is 4:3

Similarly, we can say that the ratio between the tree's height and the tree's shadow is h:21

As mentioned earlier, all height to shadow relationships will be directly proportional. 

We multiplied Anne's shadow length by 7 to get the shadow length of the tree. Since the ratios are proportional this means we can also multiply Anne's height by 7 to get the height of the tree. 

Anne's height is 4 feet so 4x7=28. The tree's height is 28 feet tall. 

Ans: The tree is 28 feet tall