$1.$ Old MacDonald had a farm called Eee$-$ooh$-$eeh$-$ooh$-$Queue. On that farm he had some ducks. And on that farm he had some goats. Eee$-$ooh$-$eeh$-$ooh$-$Queue farm has to stock duck feed and goat feed for its animals.

These feed options have some nice characteristics for modeling $($and fortunately, this is realistic!$)$ The food comes in pellet form, so it is relatively long lasting. The animals are also very consistent with how much they eat, so demand for the food is near constant $---$ Old MacDonald can perfectly predict how much he needs to feed his animals each year. Plus, he orders the feed from his next door neighbor, so there$$s no significant lead time between when he places his order and when it is delivered.