a lighthouse casts a 128-foot shadow. A nearby lampost that measures 5 feet 3 inches casts an 8 foot shadow. Write a proportion that can be used to determine the height of the lighthouse. What is the height of the lighthouse?
5 feet = 60 inches
8 feet = 96 inches
128 feet = 1536 inches
x= the height of the lighthouse
so 63 inches : 96 inches = x : 1536 inches
which is the same as 63/96 = x/1536 (this is the ratio/proportion)
then just solve for x
(cross multiply) 96x = 1536 (63)
x = 1008 inches (which is equal to 84 feet).
so the height of the lighthouse is 84 feet