On Tuesday fifty-two people ate ham sandwiches at Johnny's Deli, and half of these came down with hepatitis. The board of health discovered that the people who became ill had their ham sandwiches made by Johnny's brother, who had hepatitis at the time. This was the only relevant common element among those who got sick. Seems Johnny's brother was the cause of this outbreak. Conclusion: [Select] Method: [Select) Strong or Weak? [Select]