The blood mass of a mammal is proportional to its body mass

Question

1. The circulation time of a mammal (that is, the average time it takes for all the blood in the body to circulate once and return to the heart) is proportional to the fourth root of the body mass of the mammal. So the formula is kB^1/4. So what is the circulation time of a human with body mass 50 kilograms?
2. Kleiber's Law states that the metabolic needs (such as calorie requirements) of a mammal are proportional to its body weight raised to the 0.75 power. Surprisingly, the daily diets of mammals conform to this relation well. Assuming Kleiber's Law holds, answer this following question. If a human weighing 150 pounds needs to consume 1800 calories a day, estimate the daily calorie requirement of a horse weighing 790 lbs and of a rabbit weighing 8 lbs.
3. The blood mass of a mammal is proportional to its body mass. A rhinoceros with body mass 3000 kilograms has blood mass of 150 kilograms. Find a formula for the blood mass, M, of a mammal as a function of the body mass, B , and estimate the blood mass of a human with body mass 90 kilograms.