Final answer:
The average blood velocity in the major arteries, calculated using the principle of continuity and the given cross-sectional areas, is approximately 147.3 cm/s, which is not one of the options provided in the question.
Step-by-step explanation:
The question seeks to find the average blood velocity in the major arteries, given that the total cross-sectional area of these arteries is 20 cm² and that the typical blood velocity in the aorta is around 30 cm/s for a radius of about 1.25 cm. To find this, we use the principle of continuity where the product of cross-sectional area (A) and velocity (v) is constant for an incompressible fluid. The cross-sectional area of the aorta is π * (1.25 cm)². We can then find the velocity in the major arteries by using the formula (A1 * v1 = A2 * v2), where A1 is the cross-sectional area of the aorta, v1 is the velocity in the aorta, A2 is the total cross-sectional area of the major arteries, and v2 is the unknown velocity in the major arteries.
The cross-sectional area of the aorta, A1, is π * (1.25 cm)² = 4.91 cm², and the total cross-sectional area of major arteries A2 is given as 20 cm². Solving for v2 we have v2 = (A1 * v1) / A2 = (4.91 cm² * 30 cm/s) / 20 cm² = 147.3 cm/s. Therefore, the average blood velocity in major arteries is approximately 147.3 cm/s, which is not one of the options given, hence the correct option is not listed.