A girl is skipping stones across a lake. One of the stones accidentally ricochets off a toy boat that is initially at rest in the water (see the drawing below). The 0.082-kg stone strikes the boat at a velocity of 15 m/s, 15° below due east, and ricochets off at a velocity of 8 m/s, 12° above due east. After being struck by the stone, the boat's velocity is 1.9 m/s, due east. What is the mass of the boat? Assume the water offers no resistance to the boat's motion.