Algebra
posted by Tate .
a nickle is approximately 20mm in diameter and a quarter is about 25 mm in diameter. if the nickle is enlarges to a diameter of 128mm, what would be the diameter of the quarter using the same scale?

128 * (25/20) = 128 * 5/4 = 32*5 = 160

The electrical resistance of a wire varies directly as its length and inversely as the square of its diameter. a wire with length of 200 inches and a diameter of one quarter of an inch has a resistance of 20 ohms. find the electrical resistance in a 500 inch wire withe the same diameter