Question

At a certain time of day a person 6 ft casts a 4ft shadow. How long is the shadow cast by a 21ft tree at the same time?

Answer 1

Designate the unknown shadow length by s. Shadows cast at the same time and place are proportional to the height of the object casing the shadow. Therefore:

4/6 = s/21, or s = [4(21)]/6 = 14 feet.