A pair of long, parallel wires are carrying currents I1 and I2 exerting a force per unit length of magnitude f0 on each other. If the distance between them is changed by a factor of 1.5 and the current in both wires changed by factors of 1.7 and 2, respectively, how does the magnitude of the new force per unit length, fnew, compare to the original force, f0? Supply the missing numerical factor below.
fnew = ( )f0