Which type of transmission provides variable forward and reverse ratios?

The type of transmission that provides variable forward and reverse ratios is a Continuously Variable Transmission (CVT).

Here are the steps to understand why:

1. Manual Transmission: This type of transmission doesn't provide variable ratios. Instead, it has a fixed number of gear ratios that the driver manually selects.

2. Automatic Transmission: This type also has a fixed number of gear ratios, but the transmission system automatically selects them based on the driving conditions.

3. Semi-Automatic Transmission: This is a hybrid of manual and automatic transmissions. It allows the driver to manually shift gears without a clutch, but it doesn't provide variable ratios.

4. Continuously Variable Transmission (CVT): This type of transmission doesn't have fixed gear ratios. Instead, it continuously varies the gear ratio to provide the most efficient power delivery. This means it can provide an infinite number of ratios within a certain range, making it the only type of transmission that provides variable forward and reverse ratios.