The length of the shadow from the house is 12 m, and the length of the shadow of a 1.5 m boy is 1.2 m.

The length of the shadow from the house is 12 m, and the length of the shadow of a 1.5 m boy is 1.2 m. Find the number of floors in the house if you know that the height of one floor is 3 m.

First, we find the height of the house through the projection:
house shadow / house height = boy shadow / boy height
12 / x = 1.2 / 1.5
by the method of cross multiplication we get: x = 12 * 1.5 / 1.2
x = 15 m – house height
1st floor = 3 meters
x floors – 15 meters
x = 1 * 15/3 = 5 floors
answer 5 floors