Example 4 The Helsinki heart study asked whether the anticholesterol drug gemfibrozil reduces heart attacks. They gave the drug to 2000 men aged 40-55 and a placebo to another 2000. The probability of a heart attack for men this age in a 5-year period is 0.04. Define the random variable X to be then number of heart attacks in the drug group. Define p to be the proportion of heart attacks in the drug group. a. Use the Binomial Calculator to find the probability that the number of heart attacks in the drug group is at most 56. b. Use the Binomial Calculator to find the probability that the sample proportion of heart attacks in the drug group is at most 2.8%. c. Use the Normal Approximation to the binomial distribution to find the same probability. d. How do these results compare?