If the alternator-to-engine drive ratio is 2.55 to 1 , what rpm will the alternator have when the engine is idling at 400 rpm ? Hint. Use a direct proportion. The alternator will have \( \square \mathrm{rpm} \) when the engine is idling at 400 rpm . (Type a whole number or a decimal.)

To determine the alternator's RPM when the engine is idling at 400 RPM with an alternator-to-engine drive ratio of 2.55 to 1, you can use a direct proportion: \[ \text{Alternator RPM} = \text{Engine RPM} \times \text{Drive Ratio} \] Plugging in the values: \[ \text{Alternator RPM} = 400 \, \text{RPM} \times 2.55 = 1020 \, \text{RPM} \] So, the alternator will have **1020 RPM** when the engine is idling at 400 RPM. **Answer:** 1020