The production function of a small shop that frames pictures is

Q = 5 √LK

where Q is the number of pictures framed per day, L is labor hours and K is the machine hours.

Suppose 9 labor hours and 9 machine hours, are used every day, what is the maximum number of pictures that can be framed in a day? Calculate the marginal product of labor when 9 labor hours are used each day together with 9 machine hours. Suppose the firm doubles both the amount of labor and machine hours used per day, calculate the increase in output. Comment on the returns to scale in the operation.