Final answer:
The average arterial pressure at the entrance to the aorta in an adult is 120 mmHg for systolic pressure and 80 mmHg for diastolic pressure.
Step-by-step explanation:
The entrance to the aorta is the location where systemic arterial pressure is measured. In an adult, the average arterial pressure at the entrance to the aorta is typically around 120 mmHg. This value represents the systolic pressure, which is the maximum arterial pressure during ventricular contraction, or systole. The diastolic pressure, which is the arterial pressure during ventricular relaxation, or diastole, typically averages around 80 mmHg.