To determine the proper distance between the base of a ladder and a building, divide the used length of the ladder by ____________.

The proper distance between the base of a ladder and a building is determined by using a ratio that ensures safety and stability when the ladder is leaning against the structure. When the used length of the ladder is divided by four, it provides the ideal base-to-wall distance in feet. This ratio, often referred to as the "4-to-1 rule," is a widely accepted guideline in firefighting and ladder safety, reducing the risk of slipping or tipping over.

For instance, if a 20-foot ladder is being used, applying the 4-to-1 rule means that the base of the ladder should be positioned 5 feet away from the wall (20 feet divided by 4 equals 5 feet). This proportional relationship helps maintain the ladder's balance, ensuring that it provides a safe working platform when firefighters need to operate at height.