He places a yardstick perpendicular to the ground and measures the shadow of the tree to be 15 inches. The tree casts a 25 ft shadow. How tall is the tree?

Question

A man needs to find out how tall an  oak tree in his yard is. He places a yardstick (36 inches) perpendicular to the ground and measures the shadow to be 15 inches. The tree casts a shadow of 25 feet. How tall is the tree?

Answer 1

Here the ratio of length of the shadow to the height of the object (in this case a yardstick) is 15:36. The ratio of shadow to the height of tree will also be the same.  the shadow of tree is 25 feet long. So the height of tree will be (25*36)/15, that is 60 feet.