Final answer:
One can paint 5/3 of a wall in one hour based on the given rate, and the marginal product of the third painter is 75 square feet per hour.
Step-by-step explanation:
The question asks how much wall one could paint in an hour given a certain rate of painting. If a person paints 2/3 of a wall in 2/5 of an hour, we can calculate the rate by dividing the amount of wall painted by the time taken. The rate is therefore (2/3) / (2/5), which simplifies to (2/3) * (5/2) = 5/3. This means that the person can paint 5/3 of a wall in one hour.
Moreover, the question about the marginal product of the third painter can be answered by finding the difference in output when the third painter is added to the painting job. If two painters can paint 200 square feet and three painters can paint 275 square feet, then the marginal product of the third painter is 275 - 200 = 75 square feet per hour.