Pat takes 4 hours to brew 5 L of beer and 2 hours to make a pizza. Kris takes 6 hours to brew 5 L of beer and 4 hours to make a pizza.

Question

What is Pat and Kris's opportunity cost of making a pizza?

Think the problem through, then take a shot. The opportunity cost of making pizza is not making beer. Hint: how much beer would Pat NOT make if Pat made 2 pizzas?

Pat would not make 2.5 L of beer but i am confused about Kris.

Use the same math and procedure. For Pat, I believe you did the following calculations. To make 2 pizzas she would need 4 hours, which equals 5 L of beer -- So, one pizza would equal 2.5L of beer.

For Kris to make 1 pizza would take 4 hours or (4/6)*5 L of beer = 3.3333 L of beer. Ergo, Kris's opportunity cost for making pizza is higher than Pats. (Which will mean the Kris's opportunity cost for making beer is Lower than Pat's)