Question

"you should never buy precooked frozen foods because the price you pay includes the labor costs of preparing food." is this conclusion always valid, or can it be invalidated by the law of comparative advantage

Answer 1

For precooked frozen foods, you will always pay for the cost of packaging and the cost to get the chicken, or labor. This conclusion is always valid if you choose to buy the precooked food from the grocery store, where prices will be marked up for profit, as well.