Final answer:
When 3 people can paint 5 chairs in a day, 120 people can paint 200 chairs in a day. The marginal product of the third painter, given two painters paint 200 sq ft and three paint 275 sq ft, is 75 sq ft.
Step-by-step explanation:
If 3 people can paint 5 chairs in a day, the rate of chair painting per person is calculated by dividing the total number of chairs by the number of people. Therefore, 1 person can paint 5/3 chairs in a day. To find out how many chairs 120 people can paint in a day, you would multiply the individual rate by 120:
(5 chairs / 3 people) x 120 people = (5/3) x 120 = 200 chairs
Hence, 120 people can paint 200 chairs in a day.
Regarding the example given for reference, the marginal product of the third painter is calculated by finding the difference in the output (i.e., the square feet of wall painted) between two painters and three painters. Two painters can paint 200 square feet, and three painters can paint 275 square feet. Therefore, the marginal product of the third painter is:
275 square feet - 200 square feet = 75 square feet