Question

A water tower casts a 100- foot shadow. At the same time, an 8- foot street sign casts a shadow of 6 feet. what is the height of a tower?

Answer 1

Set up and solve an equation of ratios.  Comparing shadow lengths, we get 100/6; comparing heights, we get x/8.  Set these two ratios equal to one another and solve the resulting equation for x:

100       x
----- = ------      Then 6x=800, and x = 800 feet^2 over 6 feet.  Your answer 
   6        8

must have the unit of measurement "ft."