In a restaurant, pastichos are produced in $25$x$15$x$9$ cm trays in batches of trays per load in the oven. The temperature at which the trays come out is $175$ C and they cool naturally on a table in an environment with a temperature of $32$ C convective coefficient of $3$ W$/{}^{}$m2 K$.$ Subsequently, the pastichos are heated in microwaves from a temperature

from $40$ C to $65$ C when a customer orders this dish $($Convection coefficient inside the microwave: $90$ W$/{}^{}$m2 K$).$ Determine:

a$.$ Temperature in the center of a pasticho after four $(04)$ minutes after being removed from the oven.

b$.$ How long would an employee have to program the microwave if a customer orders a pastry?