Answer: ok f(t) is a function that says how the temperature of the turkey change as the time goes. When it says that the time is and independent variable and the temperature the dependent variable, it means that the time not depends on anything, you can let the turkey in the oven as much time as you want, but the temperature depends on the time the thing was on the oven, ence the temperature is dependent.
when yo say that the turkey was removed after 360 mins, this means that our function f(t) goes from t = 0mins to t =360mins, if the temperature of the oven remains constant, then the temperature of the turkey can only augment as a the time pases, until it has the same value than the temperature of the oven.