2005 AMC 12B Problem 1

The troop buys $1000 \div 5 = 200$ groups of five bars, costing $200 \cdot 2 = 400$ dollars. They sell $1000 \div 2 = 500$ pairs of bars, earning $500 \cdot 1 = 500$ dollars. The profit is $500 - 400 = 100$ dollars. Thus, the correct answer is A.