Billy's mom sends him to get ketchup. She gives him $10 and tells him to get the best deal on ketchup that he can and to spend all $10 on ketchup. He finds a bottle with 10 oz that cost $1 each. He finds a bottle that costs $2 that contains 16 ounces. He finds a bottle with 25 ounces that costs $2.5. He finds a $5 bottle that contains 50 ounces. Finally, he finds a $10 bottle with 200 ounces. How many bottles of ketchup does he buy? Let's think first. Chain of thought:
The 10 ounce bottle costs $.1 an ounce because 1 / 10 = .1. The 16 ounce bottle costs $.125 an ounce because 2 / 12 = .125. The 25 ounce bottle costs $.125 an ounce because 2.5 / 20 = .125. The 50 ounce bottle costs $.1 an ounce because 5 / 50 = .1. The 200 ounce bottle cost $.05 an ounce because 10 / 200 = .05. The 200 ounce bottle is the cheapest per ounce because .05 < .08 < .1 < .125. He buys 1 bottle of ketchup because 10 / 10 = 1.
Therefore, the answer is 1.