UPDATE: After determining which area to focus on, you get a list of the items served. You create the following chart for each food item and how many people ate the item along with the number of people who ate it and are ill. Calculate the attack rate of each food item in order to determine the source of the outbreak. Food Item Number of sick people who ate this food Number of not sick people who ate this food Veggie tray with dip 81 13 Potato salad 137 53 Salmon with dill sauce 58 12 Sliders 147 85 Alcoholic smoothies 173 49 Chicken 152 61 Cheesecake 134 78