Variation Question

Question

The resistance, R, of a wire varies directly as its length and inversely as the square of its diameter. If the resistance of a wire 2500⁢ft long with a diameter of 0.23 inches is 11617 ohms, what is the resistance of 4700⁢ft of the same type of wire with a diameter of 0.02 inches? (Leave k in fraction form or round to at least 3 decimal places. Round off your final answer to the nearest hundredth.)

Answer 1

The formula, given in words, is R = kL/d² and I urge you to study your chapter on variations. k is the 'constant of proportionality;' it can be computed by substituting R, L and d from the beginning of the second sentence (before the comma). Then when you know k, you can answer the final part of the question.