Final answer:
To find the percent profit made by the department store, divide the profit by the cost and multiply by 100.
Step-by-step explanation:
To find the percent, we need to calculate the profit made by the department store. The cost of buying 400 shirts at $7,200 is $7,200 and the selling price of each shirt is $20. So, the revenue from selling all 400 shirts is $20 * 400 = $8,000.
Now, we can calculate the profit made by subtracting the cost from the revenue: $8,000 - $7,200 = $800.
To find the percent, divide the profit by the cost and multiply by 100: ($800 / $7,200) * 100 = 11.11%.