For questions 1-7, refer to the following information : Thrombolytic drugs are substances that cause the breakdown of blood clots obstructing the flow of blood through the vessels . They are used by injection during or shortly after a heart attack or stroke to prevent clots from blocking blood flow to the heart muscle or brain . In an experiment , three thrombolytic treatments were studied : streptokinase (SK ), accelerated alteplase (AtPA ) and streptokinase plus alteplase (SK + (PA ). A total of 4082 patients affected by Acute Myocardial Infarction (AMI ) participated in the study . Each patient received one of the drugs , randomly assigned , shortly after the infarction . Efficacy was measured by the mortality at 30 to 35 days . The data are summarized in the following table . Using a 0.05 significance level , you need to test the claim that survival is associated with the type of thrombolytic drug by answering the following questions . (7 points )