Doris's four-unit apartment building has each unit rented at $500 a month. Considering a 10% vacancy rate and $500 income from a coin-operated washer and dryer, what is the potential gross income?

To determine the potential gross income for Doris's four-unit apartment building, one first calculates the total income generated from the rental units and any additional sources of income, such as the coin-operated washer and dryer.

Each of the four units is rented for $500 per month. Therefore, the total monthly rental income from the four units can be calculated as follows:

4 units x $500/unit = $2,000 per month

Over the course of a year, this amounts to:

$2,000/month x 12 months = $24,000 per year from rent alone.

Additionally, Doris receives $500 per year from the coin-operated washer and dryer. This income can be added to the total rental income:

$24,000 (rental income) + $500 (washer and dryer income) = $24,500.

However, since the question asks for the potential gross income, and vacancy rates typically affect the effective income rather than the gross income calculation, we usually do not subtract for vacancy when determining potential gross income.

Given these calculations, the total potential gross income for the apartment building is:

$24,500.

Thus, the correct choice is derived from focusing on the annual income elements without deduction for vacancies, aligning with the