The average selling price is more difficult to determine, for it seldom happens that all the lots are sold at the same price. Corner lots and the larger lots command a higher price than others. Moreover, if the development of a particular tract has been successful, prices advance from time to time and a late purchaser may have to pay a higher price. It may also happen that one purchaser will buy a number of lots and thereby obtain a reduction from the current schedule.

Under such circumstances, the actual average selling price of the lots covered by the open contracts should be obtained by listing the original amount of all the open contracts, and dividing this total by the number of lots included in those contracts.