To determine the increase in total product when labor increases from four to five workers, we need to use the marginal physical product (MPP). The MPP represents the additional output (sandwiches per hour, in this case) produced by adding one more worker.

According to the table:

• At 4 workers, the MPP is 12 sandwiches per hour.
• At 5 workers, the MPP is 10 sandwiches per hour.

The increase in total product when the labor increases from 4 to 5 workers is the marginal physical product of the 5th worker, which is 10 sandwiches per hour.

Would you like to explore more details on MPP and its implications?

Here are 5 related questions to expand on the topic:

1. How do you calculate the total product (TP) from MPP?
2. What does diminishing marginal returns mean in this context?
3. How does MPP affect the average product (AP)?
4. What would happen if labor increased further? Can you predict MPP trends?
5. How do firms use MPP to make decisions about hiring?

Tip: In economics, MPP typically decreases as more labor is added due to diminishing returns, meaning each additional worker adds less to total output.