The Resistance, R, of a wire varies directly as its length and inversley as the square of its diameter. If the resistance of a wire 2600 feet long with a diameter of 0.22 inches is 18498 ohms, what is the resistance of 3800 feet of the same type of wire with a diameter of 0.42 inches? (Leave K in fraction form or round atleast 3 decimal places. Round off your final answer to the nearest hundredth)

7418.11 ?

Correct Thanks!

Are you sure? I wasn't certain I was working it correctly.

no need to use pi at all for his problem, just calculate (19^2/13^2) to get the proportion and multiply with 530.66
which gives you 1133.54 as per how the question was given

Yes. I see how that would do it. It just seems like an odd way to go about it when there is already a handy formula for the area of a circle.

for the problem as stated in the op there is no need to know the formula or the value of pi