Skafic Corporation, a smartphone manufacturer, normally produces and sells between 10,000 and 15,000 units per year. The following cost data apply to various activity levels. 10,000 12,000 14,000 15,000 Number of Units Total costs incurred Fixed $ 75,000 100,000 Variable Total costs Cost per unit Fixed Variable Total cost per unit $175,000 $ 7.50 10.00 $17.50 Required a. Complete the preceding table by filling in the missing amounts for the levels of activity shown in the first row of the table. Round all cost-per-unit figures to the nearest whole penny. b. Explain why the total cost per unit decreases as the number of units increases.