Question: One US cup equals 250ml. Brian is making lasagna for himself, his wife, his two kids, his parents, and his wife's parents. The recipe requires 1/2 a cup of milk per serving. How many 1L cartons of milk does Brian need to buy if each person is expected to eat 2 servings? Think carefully first, then make a decision:
There will be a total of (1) Brian + (1) Brian's wife + (2) two kids + (2) Brian's parents + (2) Brian's in - laws = 1 + 1 + 2 + 2 + 2 = 8 people eating. If 1 person eats 2 serving of lasagna then 8 people will eat 8 * 2 = 16 servings. If each serving requires 1 / 2 cup of milk then 16 servings require 16 * 1 / 2 cups = 8 cups of milk. If one cup of milk equals 250 ml, then 8 cups of milk equal 8 * 250 = 2000 ml of milk. 1L carton of milk equals 1000ml of milk, therefore Brian needs 2000 / 1000 = 2 cartons of 1L milk. So the answer is 2.