When a five-speed transmission is in fourth gear, which statement is accurate?

In a five-speed transmission, being in fourth gear typically means that the gear ratio is 1:1. This ratio is significant because it indicates that the engine RPMs and the output RPMs are the same, allowing for direct drive without any additional gearing. This is essential for maintaining efficiency at higher speeds, such as when cruising on the highway.

Additionally, the 3-4 synchronizer being engaged is important in ensuring that fourth gear is properly selected and that the input shaft gear is in alignment with the output shaft gear during operation. The synchronizer serves as a mechanism to match the speeds of these gears for smooth engagement, preventing grinding and ensuring a seamless gear shift.

Therefore, both statements regarding the gear ratio and the engagement of the 3-4 synchronizer are accurate, making the combination of these facts the correct answer. The presence of both elements in fourth gear captures the key mechanical functions of the transmission at that specific gear engagement.