Fifty students went to a school reception. Immediately after the reception, 20 students had diarrhea. A professor believed that students got diarrhea because they ate bad blue cheese at the reception. He found thirty students ate blue cheese and fifteen of them got diarrhea. Twenty students did not eat blue cheese, but still five of them got diarrhea.The professor decided to use Chi-square test to examine the relationship between consuming blue cheese and diarrhea.The summarized data shows the expected frequency (in parenthesis)

Outcome Diarrhea Non-Diarrhea Sum Exposure 15 15 Ate Blue Cheese (12) (18) 30 5 15 Did not eat Blue Cheese (8) (12) 20 Total 20 30 50 What's the Chi-square value