Question

A building has a shadow that is 25 feet long. A person 6 feet tall cast a similar shadow. How long is the person's shadow?

Answer 1

The answer is in the question. If it is a similar shadow wouldn't it be the same?
25 feet

You can solve these word problems using ratios and proportions.

Answer 2

Imagine the side of the building is one side to a triangle and the second would be from the top of the building to the point where the shadow ends and the third is from the base of the building to the point where the shadow ends. Just use the pythagoreon theorem to find stuff. I can't solve the problem you gave because you would need the height of the building