A 2013 study examined using copper bed rails in hospital intensive care units (ICU) as a way to prevent hospital-acquired bacterial infections (HAI). Patients admitted to the ICU were randomly assigned to a bedroom with either copper or regular surfaces. Of the 294 patients assigned to the copper bedroom, 21 developed an HAI. By comparison, 41 of the 320 patients assigned to the regular bedroom developed an HAI.

1. Obtain the test statistic. Give your answer as a numerical value rounded to 2 decimal places (for ex. 1.11, no text).