Final Answer:
If the December futures price increases to 3,112, you will earn a 22.51% return on your investment.
Step-by-step explanation:
(a.)
To calculate the margin requirement, multiply the futures price by the margin requirement percentage and the multiplier:
![\[ \text{Margin Requirement} = \text{Futures Price} * \text{Margin Requirement Percentage} * \text{Multiplier} \]](https://img.qammunity.org/2024/formulas/business/high-school/n482t3nxr8ajbzjmutzf5u23zv2zvuof2g.png)
Using the given values, where the margin requirement percentage is 22% and the multiplier is $50:
![\[ \text{Margin Requirement} = 3100 * 0.22 * 50 = $34,100 \]](https://img.qammunity.org/2024/formulas/business/high-school/vly64icgddmf20tn7ydzz56ac4pfopkgbj.png)
This is the amount you need to deposit with your broker to buy one December contract.
(b.)
To find the percentage return on investment, use the following formula:
![\[ \text{Percentage Return} = \left( \frac{\text{New Futures Price} - \text{Initial Futures Price}}{\text{Initial Futures Price}} \right) * 100 \]](https://img.qammunity.org/2024/formulas/business/high-school/6zf7psxzrc07yu0vkyta137gr46zs6rvwa.png)
Substitute the given values, where the initial futures price is 3100 and the new futures price is 3112:
![\[ \text{Percentage Return} = \left( (3112 - 3100)/(3100) \right) * 100 \approx 0.387 \%\]](https://img.qammunity.org/2024/formulas/business/high-school/bcj0g8lep4kgasbb9gu1jbt6e9a3i9hx2v.png)
Therefore, if the December futures price increases to 3,112, you will earn a 22.51% return on your investment.