Required information [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: Units Total Shipping Month January Shipped Expense 4 $ 2,100 February 7 $ 2,600 March S $2,000 April 6 $ 2,300 May 8 $ 2,600 June 9 $3,600 July 2 $ 1,500