Your answer is incorrect.

Annealing is a process by which steel is reheated and then cooled to make it less brittle. Consider the reheat stage for a $100-$mm$-$thick steel plate $(=7830k\frac{g}{m^3},c=550\frac{J}{k}g*K,k=48\frac{W}{m}*K),$ which is initially at a uniform temperature of $T_i=260C$ and is to be heated to a minimum temperature of $550C.$ Heating is effected in a gas$-$fired furnace, where products of combustion at $T_{}=800C$ maintain a convection coefficient of $h=250\frac{W}{m^2}*K$ on both surfaces of the plate. How long should the plate be left in the furnace?

The plate should be left in the furnace for $$ sec$.$ Physical Properties Mathematical Functions