To address the question, we need to understand the concepts of area rate and flow rate concerning the engine speed (measured in revolutions per minute, or rpm) and the tractor speed (measured in miles per hour, or mph).
### Step-by-step Analysis
1. Engine Speed and Area Rate:
- The area rate is typically associated with the engine speed (rpm).
- If the engine speed decreases, the engine is making fewer revolutions per minute.
- Consequently, the area rate would decrease because the engine is operating at a slower pace.
2. Tractor Speed and Flow Rate:
- The flow rate is typically associated with the tractor speed (mph).
- If the tractor speed increases, it signifies the tractor is moving faster.
- As the tractor speed increases, the flow rate increases because the tractor covers more distance in less time.
### Application to the Given Scenario
- The problem states that shifting into third gear decreases the engine speed (rpm).
- Simultaneously, the tractor speed (mph) increases.
From our analysis:
- With a decrease in engine speed (rpm), the area rate would decrease.
- With an increase in tractor speed (mph), the flow rate would increase.
### Conclusion
Based on the detailed analysis, the correct effect of shifting into third gear would be:
- Area rate would decrease (due to a decrease in engine speed).
- Flow rate would increase (due to an increase in tractor speed).
Therefore, the correct option is:
C. Area rate would decrease and flow rate would increase.
