A girl is skipping stones across a lake. One of the stonesaccidentally ricochets off a toy boat that is initially at rest inthe water (see the drawing). The 0.072-kg stone strikes the boat ata velocity of 13 m/s, 15° below due east, and ricochets off ata velocity of 11 m/s, 12° above due east. After being struck bythe stone, the boat's velocity is 2.1 m/s, due east. What is the mass of the boat? Assume the water offers no resistance to theboat's motion.