Required information [The following information applies to the questions displayed below.] Phillips Company manufactures air-conditioning units for commercial buildings and has noticed considerable variation in shipping expenses from month to month as per the data below: Month January February March April May June July Units Shipped 4 4 5 2 3 6 8 Total Shipping Expense $ 1,960 $ 2,860 $ 2,300 $ 1,254 $ 2,010 $ 2,640 $ 3,744 Required: 1. Which two months should be used if Phillips wants to estimate the behaviour of shipping expenses using the high-low method? Month High activity level Low activity level Shipping Expense $ 3,744 $ 1,254