#4) Voltage = summation of I*R, so since the initial voltage is V, and the final voltage is zero going through the circuit, the voltage drop is V=IR through each resistor. However, since they are in series, you add them V=IR(1)+IR(2). This relation shows that the voltage drop is the same through each resistor. #5) Since the small piston is 1/3 surface area of the large piston, it will displace 1/3 less liquid if moved a specified distance. So, to raise the large piston one inch, we need to move one that much liquid; which means that the small piston must move 3 inches. Hope that helps.