Four surgical procedures currently are used to install pacem

Four surgical procedures currently are used to install pacemakers. If the patient does not need to return for follow-up surgery, the operation is called a \"clear\" operation. A heart center wants to compare the proportion of clear operations for the 4 procedures, and collects the following numbers of patients from their own records: They will use this information to test for a difference among the proportion of clear operations using a chi-square test with a level of significance of 0.01. The test will involve____ degrees of freedom. The expected cell frequency for the Procedure D/Return cell is____ The critical value of the test is ____.

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