Question

If a 5 foot post casts an 8 foot shadow at the same time that a nearby tree casts a 48 foot shadow how tall is the tree

Answer 1

The first thing we are going to assume for this case is that the tree and the post are located in the same place.
 From that place, both cast a shadow in the same direction.
 We then have two similar triangles.
 Therefore, we have the following relationship:
 $\frac{x}{48} = \frac{5}{8}$
 From here, we clear the value of x.
 We have then:
 $x = \frac{5}{8} *48$
 Rewriting:
 $x=30$
 Answer:
 the tree is 30 feet tall