The length of a shadow of a flagpole was found to be 72 feet. the shadow of a 3 foot picket fence in line with the flagpole was 4 feet. what is the height of the flagpole?

Please have a look at diagram attached.

Let the height of the pole is H and its shadow is 72 ft.

The height of the fence is 3 ft and its shadow is 4 ft.

Both are similar triangles.

H/72 = 3/4

Cross multiplying

4 H = 72*3

4 H = 216

Dividing by 4

H = 54 feets : Answer

Hope that will help :)