In the circuit below, G1 = 28 mS, G2 = 50 mS, G3 = 46 mS, G4 = 32 mS, G5 = 42 mS. What resistance is measured at the terminals of the network below if the switch is: (a) open (open circuit) (b) closed (short circuit) (c) replaced by a 7 mS conductance