GRB Co. recorded the following cost data for the first four months of 2021. The data applies to its product BAC. GRB produced 640 units in January and total cost equaled $12,240; 683 units were produced in February with total cost equal to $12,185; 832 units were produced in March with total cost equal to $13,632; 750 units were produced in April with total cost equal to $12,605. What is the difference between the high total costs and the low total costs for the high and low data points