Final answer:
The number of blood cells passing through a 243 kg bear's major artery each millisecond is 4131.
Step-by-step explanation:
To find the number of blood cells passing through a 243 kg bear's major artery each millisecond, we can use the formula B = 17m^3, where B represents the number of blood cells and m represents the animal's mass in kilograms. Plugging in the mass of the bear, we have B = 17(243) = 4131 blood cells passing through the artery each millisecond. Therefore, the number of blood cells passing through a 243 kg bear's major artery each millisecond is 4131.