High-Low Method to Determine Fixed Cost and Variable Rate Dohini Manufacturing Company had the following 12 months of data on purchasing cost and number of purchase orders. Number of Purchase Purchasing Month Cost Orders January $18,860 370 February 18,040 320 March 19,250 370 April 18,050 410 May 19,345 400 June 19,500 450 July 19,670 460 August 20,920 560 September 19,430 440 October 20,020 500 November 18,800 470 December 19,340 480