Final answer:
The given demand equation cannot be used to directly find the number of donuts demanded since it is for personal pizzas. The substitution method shows that the quantity demanded would be 8, which is not an option provided. Therefore, additional information is needed to answer the question correctly.
Step-by-step explanation:
The question asks to determine the number of donuts demanded by consumers given the price of each donut. We are given a similar example with personal pizzas.
Using the demand equation Qd = 16 - 2P, where Qd is the quantity demanded and P is the price, we can find the quantity demanded for donuts. In this case, for donuts priced at $4.00 each, we substitute P with 4 into the equation and get:
Qd = 16 - 2(4)
Qd = 16 - 8
Qd = 8
However, since the answer choices provided in the question (5, 10, 15, 20) do not include 8, this means that the provided demand equation and price for personal pizzas cannot be used directly to answer the question about the number of donuts. Additional information or the correct demand equation specific to donuts would be required to determine the accurate demand.