Two blocks hang from strings going around pulleys of different diameter that are connected, as shown in the figure. The large pulley has a radius of R = 9.0 cm and and the small pulley has a radius of r = 2.3 cm. The mass of the block that hangs from the small pulley is m = 3.71 kg. What is the mass of block M that hangs from the large pulley to keep the block m from falling?