A small garment factory produces hand-painted t-shirts for the local market. Monthly sales for the t-shirts have an average of 100 t-shirts with a standard deviation of 8 t-shirts. The selling price per t-shirt is $200. On average, 100 t-shirts are produced. Production is also known to have a standard deviation of 5 t-shirts. Each unit has a variable cost of $120. Sales and the number of units produced have a correlation of 0.05. What is the variance of the profit margin (total income minus variable cost) for this factory