An iron block of unknown mass at 185F is dropped into an insulated tank that contains 0.8

Question:

An iron block of unknown mass at 185°F is dropped into an insulated tank that contains 0.8 ft3 of water at 70°F. At the same time, a paddle wheel driven by a 200-W motor is activated to stir the water. Thermal equilibrium is established after 10 min with a final temperature of 75°F. Determine
(a) The mass of the iron block and
(b) The entropy generated during this process.