Cholesterol levels are measured for 28 heart attack patients (2 days after their attacks) and 30 other hospital patients who did not have a heart attack. For the 28 heart attack patients, the mean cholesterol level was 253.9 with a standard deviation of 47.7. For the 30 other hospital patients who did not have a heart attack, the mean cholesterol level was 193.1 with a standard deviation of 22.3. At the 0.05 significance level, is the cholesterol level higher for the heart attack patients?