4.—(1) Subject to sub-paragraph (2), the average price shall be such amount as may be obtained by dividing the total amount of the prices shown in returns, furnished under paragraph 2, for a 4 week period as having been paid for animals by the total number of the animals stated in those returns to have been sold.
(2) Before the Department proceeds to make a calculation of an average price it shall have obtained returns for sales of not less than 100 animals during a 4 week period.
(3) Where in any 4 week period the requirements of sub-paragraph (2) are not met, the average price for that 4 week period shall be the same amount as the most recent average price calculated in accordance with sub-paragraphs (1) and (2).