in reply to
So it's homework - so what?
As a side note: Who cooks a roast at 200C? That's way too hot. 160C or 150C is a much better temperature for something like a roast.
Onto the topic: Homework problems where the poster just asks for the answer bother me--because it's possible I might have to work with this guy if he goes on to program professionally. Knowing where to look and how to ask the question is indeed an important skill, but you still need a significant amount of "in-the-field" knowledge to be proficient in anything.