To calculate the attack rate for each food item using 250 as a constant denominator, we use the formula: $$ \text{Attack Rate} = \frac{\text{Number of people who ate a specific food and got sick}}{\text{Total number of attendees (constant)}} \times 100\% $$ 1. Attack Rate for Rice Step 1: Identify the number of people who ate rice and had diarrhea. Number of people who ate rice and had diarrhea = 12 Step 2: Use the constant total number of attendees. Total attendees = 250 Step 3: Calculate the attack rate for rice. $$ \text{Attack Rate (Rice)} = \frac{12}{250} \times 100\% $$ $$ \text{Attack Rate (Rice)} = 0.048 \times 100\% $$ $$ \text{Attack Rate (Rice)} = 4.8\% $$ The attack rate for rice is $\boxed{\text{4.8\%}}$. 2. Attack Rate for Swallow Step 1: Identify the number of people who ate swallow and had diarrhea. Number of people who ate swallow and had diarrhea = 17 Step 2: Use the constant total number of attendees. Total attendees = 250 Step 3: Calculate the attack rate for swallow. $$ \text{Attack Rate (Swallow)} = \frac{17}{250} \times 100\% $$ $$ \text{Attack Rate (Swallow)} = 0.068 \times 100\% $$ $$ \text{Attack Rate (Swallow)} = 6.8\% $$ The attack rate for swallow is $\boxed{\text{6.8\%}}$. 3. Attack Rate for Beans Porridge Step 1: Identify the number of people who ate beans porridge and had diarrhea. Number of people who ate beans porridge and had diarrhea = 7 Step 2: Use the constant total number of attendees. Total attendees = 250 Step 3: Calculate the attack rate for beans porridge. $$ \text{Attack Rate (Beans Porridge)} = \frac{7}{250} \times 100\% $$ $$ \text{Attack Rate (Beans Porridge)} = 0.028 \times 100\% $$ $$ \text{Attack Rate (Beans Porridge)} = 2.8\% $$ The attack rate for beans porridge is $\boxed{\text{2.8\%}}$. 3 done, 2 left today. You're making progress.