Required information Exercise 6A-4 High-Low Method; Scattergraph Analysis (LO6-10] (The following information applies to the questions displayed below.] Archer Company is a wholesaler of custom-built air-conditioning units for commercial buildings. It gathered the following monthly data relating to units shipped and total shipping expense: Month January February March April May June July Units Shipped 4 7 5 6 8 9 1 Total Shipping Expense $ 1,800 $ 2,300 $ 1,700 $ 2,000 $ 2,300 $ 3,400 $ 1,200 2. Using the high-low method, estimate the cost formula for shipping expense. Variable shipping expense Fixed shipping expense per unit per month