The increase in value of a home due to the addition of central air conditioning is best estimated by using

This choice suggests that the entire expense of purchasing and installing air conditioning directly translates to increased home value. However, the actual market value increase is influenced more by buyer willingness to pay rather than just the installation cost, which may not be fully reflected in the sale price.

Like the previous option, this choice implies a fixed percentage of the installation cost will contribute to the home's value. However, this does not take into account market conditions or the specific desirability of air conditioning in the area's housing market, making it an unreliable estimate.

This option assumes that only the cost of the air conditioning unit itself contributes to the home's value. In reality, both the unit and its installation are critical to determining value, as an installed system is what buyers are actually paying for, not just the equipment.