please help me i suck at math..

Question

a lamp pole with a height of 10ft cast a shadow of 3ft . what is the height of a building that cast  a shadow of 15ft at the same time??

Answer 1

Hi Jessi,

 

This is a proportion question.

 

if a pole 10 ft high casts a shadow of 3 ft

 a pole x ft high cats a shadow of 15 ft

 

10       3

---- = ----

x         15

 

Take the cross product to solve for x.

3x = 10*15

3x = 150

x = 50 ft (the height of the building whose shadow is 15 ft)

 

Answer 2

Let h = the height of the building

10/3 = h/15      Cross multiply

3h = 150

h = 50 feet