Final answer:
To determine the factor by which a human's metabolic rate exceeds that of a cat, the formula MR ≈ m^{3/4} is used. By calculating (70.0 kg)^{3/4} ÷ (4.91 kg)^{3/4}, the result is a unitless number indicating the factor difference.
Step-by-step explanation:
To find by what factor the metabolic rate of a 70.0-kg human exceeds that of a 4.91-kg cat, given that the metabolic rate (MR) is proportional to the body mass (m) raised to the power of 3/4, we can use the formula:
MR ≈ m^{3/4}
For the human, MR_human ≈ (70.0 kg)^{3/4} and for the cat, MR_cat ≈ (4.91 kg)^{3/4}. To find the factor by which the human's MR exceeds the cat's, you divide the human's MR by the cat's MR:
Factor = ÷ MR_human/MR_cat
Calculating this gives us:
Factor = (70.0 kg)^{3/4} ÷ (4.91 kg)^{3/4}
After computing the values, you arrive at the factor by which a human's metabolic rate is higher than that of a cat. Note that the units of kilograms cancel out, so the factor is a unitless number.