Question

A 15 foot tree cast a 5 foot shadow. Another tree cast a 17.5 foot shadow. How tall is the tree that cast a 17.5 foot shadow?

Answer 1

52.5 ft

Explanation:

Let:

x = tree height of the tree with a 17.5 ft shadow

Ratio of tree height to shadow length:

15 : 5 →
`(15)/(5)`

x : 17.5 →
`(x)/(17.5)`

The ratios are the same so they can be used to construct an equation, which can be solved to find x:

`(x)/(17.5) = (15)/(5) \\\\ x = 3(17.5) \\\\ x = 52.5`