If a developer wants to create 20 lots with each lot measuring 21,780 square feet, how many acres would be needed for this project?

To determine the number of acres needed for the development of 20 lots, each measuring 21,780 square feet, we start by calculating the total area required in square feet.

First, multiply the number of lots by the size of each lot:

20 lots × 21,780 square feet per lot = 435,600 square feet

Next, we need to convert square feet into acres, knowing that 1 acre is equivalent to 43,560 square feet. To find the total area in acres, divide the total area in square feet by the number of square feet in an acre:

435,600 square feet ÷ 43,560 square feet per acre = 10 acres

Therefore, the developer needs a total of 10 acres to create the 20 lots of the specified size, making this the correct answer.