A circumferential fin of rectangular profile is constructed of a material having k = 55 W/m-°C and is installed on a tube having a diameter of 3 cm. The length of the fin is 3 cm and the thickness is 2 mm. If the fin is exposed to a convection environment at 20 °C with a convection coefficient of 68 W/m²-°C and the tube wall temperature is 100 °C, calculate the heat lost by the fin.