As shown in the figure, a battery with internal resistance r…

As shown in the figure, a battery with internal resistance r has initially no load connected across its terminals. Then the switches S1 and S2 are closed successively. The ammeter connected to the 6Ω resistor reads 1.875 A when S1 is closed, then 1.667 A when both S1 and S2 is closed. What is the internal resistance of the battery, in ohms, to two significant figures?