Scattergraph Method, High-Low Method Deepa Dalal opened a free-standing radiology clinic. She had anticipated that the costs for the radiological tests would be primarily fixed, but she found that costs increased with the number of tests performed. Costs for this service over the past nine months are as follows: Month Radiology Tests Total Cost January 2,800 $133,500 February 2,600 135,060 March 3,100 175,000 April 3,500 170,600 May 3,400 176,900 June 3,700 186,600 July 3,840 174,450 August 4,100 195,510 September 3,450 185,300