Let's solve this step by step.

Given Information:

• The engineer currently has 30 workers.
• The project is estimated to take 28 weeks with these 30 workers.
• The owner wants the project completed in 20 weeks.

Step-by-Step Solution:

The amount of work done is proportional to the number of workers and the time. In this case, we can assume the work is constant and apply the formula:

$\text{Work} = \text{Workers} \times \text{Time}$

Using this, let's express the work done by the current workers: $\text{Work} = 30 \times 28 = 840 \text{ worker-weeks}$

Now, let the number of workers needed to finish the job in 20 weeks be $x$. The amount of work is the same, so we set up the equation: $x \times 20 = 840$

Solving for $x$: $x = \frac{840}{20} = 42 \text{ workers}$

So, 42 workers are required to finish the project in 20 weeks.

Final Answer:

The engineer currently has 30 workers, so the additional number of workers needed is: $42 - 30 = 12 \text{ workers}$

The engineer needs to hire 12 more workers to meet the owner's deadline.

Would you like further details or have any other questions?

Here are 5 related questions to explore further:

1. What would happen if the owner wants the project finished in 15 weeks instead?
2. How long would it take with 50 workers on the project?
3. If the number of workers is doubled, how will the project duration change?
4. How would this change if the owner extended the deadline to 30 weeks?
5. How many workers would be needed to finish the project in half the original time (14 weeks)?

Tip: Always remember that work is proportional to the number of workers and the time, so adjusting one affects the other!