A portable recharging device can recharge 3 batteries at once, and it can charge the batteries while itself being charged from an outlet. The device can recharge a single dead battery in 3 hours, and it can be completely recharged from an outlet in 2 hours when it contains no batteries. A fully discharged device holding 3 dead batteries is plugged into an outlet. If the capacity of a battery is one-third the capacity of the device, and the device and batteries charge at constant rates, how much time will pass before the device is completely recharged?

a) 5 hours
b) 6 hours
c) 8 hours
d) 9 hours
e) 11 hours


OA B

Source: Princeton Review