A sales budget is given below for one of the products manufactured by Dollie (Pty) Ltd: The inventory of finished goods at the end of each month must be equal to 5,000 units plus 10% of the next month's sales. On June 30 , the finished goods inventory totaled 6,800 units. Each unit of product requires three kilograms of a special substance extract known as QP-10. Sometimes the substance is in short supply; for this reason, the company has a policy of maintaining an inventory at the end of each month equal to one half of the next month's production needs. This requirement was met on July 1 of the current year. Required: Prepare a budget showing the quantity of QP10 to be purchased for September