How tall is that flag pole to the nearest foot?

Question

A 12-foot tall house casts a shadow that is 9 feet long. At the same time, a nearby flag pole casts a shadow that is 15 feet long. How tall is that flag pole to the nearest foot?

Answer 1

A 12 foot tall house casts a 9 foot shadow.  That means the ratio of the height of the object to the shadow length is

 

12/9 = 4/3.  

 

If a shadow is 15 feet long, then length of flag pole / 15 ft shadow = 4/3

length / 15 = 4/3

length= 15 * 4 / 3 = 20 feet