thx, according to the question, T,in is 50 C and T,out is 4 C

A spherical research probe consists of two concentric hollow spherical layers, which surround an instrument package. The inner most shell has an inside radius of 25cm and is made from mild steel with a k=60.5 W/(mK). The outer shell is stainless steel with a k=14.9W/(mK). Each layer is 2.5cm thick. There is a thermal contact resistance of 0.00022(m2K)/W between the two shells. The probe is surrounded by water at 4C. The convection heat transfer coefficient between the external surface and the water is 1000W/(m2K). The inside shell wall temperature is 50C. Calculate the power output of the instrument package under these conditions