First you need to know the equation for inverse variation. y = k/x Next, fill in the information you know so that you can find 'k', the constant of variation. 9 = k/3 Now solving for k we get k = 27 and you have your inverse equation for this problem and can use any values for intensity or resistance. y = 27/x or I = 27/R 18 = 27/R 18R = 27 R = 27/18 R = 1.5 ohms
