Answer:
Roughly the same, larger.
Step-by-step explanation:
The mammals have four chambered heart and double circulation occurs in mammals that separates the oxygenated and deoxygenated blood in mammals and saves the energy.
The oxygen needs to diffuse in each and every cell of the body. The distance of the oxygen diffusion is almost same in the whales and other mammals. The distance of bulk flow of oxygen depends on the total surface area and inversely proportional to it. The humans body small is small as compared to whales and has less distance where blue whale has the large distance of bulk flow for oxygen.
Thus, the answer is roughly the same, larger.