When a firm uses four machines, it can produce 400 units daily. A fifth machine allows the firm to produce 560 units.

Which of the following statements is true regarding production?

• a.)
• The average product for the fifth machine is 32 units.
• b.)
• The total product for the ninth machine is 960 units.
• c.)
• The marginal product for the fifth machine is 160 units
• d.)
• The average product for the fourth machine is 40 units.