Physician's Health Study Two groups each of 11,037 male physicians were tested to see if taking an aspirin daily reduces the chance of suffering a heart attack. In the group that took an aspirin daily, 104 experienced a heart attack within 5 years, while 189 in the group that did not take an aspirin daily had experienced a heart attack with 5 years. (a) Perform a hypothesis test to see whether the aspirin routine is significantly better than a placebo (no treatment) at reducing the occurrence of heart attacks, that is, if pa< Pne where pa is the proportion who experienced heart attacks using the aspirin routine, and PN is the proportion who experienced heart attacks without the aspirin routine. Use a 5% significance level and a normal distribution (b) Can a causal relationship be inferred from the results?