A researcher is interested in examining the cholesterol levels of heart-attack patients. 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. The researcher believes that cholesterol levels will be higher for the heartattack patients. Random samples from each group provide the following results:

Heart-Attack Patients Non-HeartAttackPatients

Sample Size 28 30

Mean Cholesterol (mg/DL) 213.9 193.1

Standard Deviation of Cholesterol (mg/DL) 47.7 22.3

Assume that the cholesterol levels for both populations are normally distributed and that the population standard deviations are equal.

Using a 5% significance level, can the researcher conclude that the mean cholesterol level of heartattack patients is greater than the mean cholesterol level of non-heart-attack patients? Formulate and test the appropriate hypotheses. State and explain your conclusion within the context of the question. Use the critical value approach.