Answer: 30 pieces of pottery
Step-by-step explanation:
The marginal product could simply be explained as the resulting change in output as a result of employing one more unit of labor (input).
When Kate works alone ; pieces of pottery made = 25 pieces
Output when she employed her sister (Kate) and they work together, output = 55 pieces
Hence, Kate's marginal product ;
55 pieces - 25 pieces = 30 pieces