Joseph wants to know which brand of fish food will make his goldfish grow the largest. He has 15 goldfish in each of his three 10-gallon tanks. In tank #1 he fed the fish his usual fish food, GrowBig. In the tank #2 he fed the fish Goldfish Goodies fish food. In tank #3 he fed the fish Lets Eat fish food. All three tanks received 10 grams of food per day. After 6 weeks the goldfish who were fed GrowBig had grown an average 2cm. The fish that ate Goldfish Goodies grew 4cm. The fish that are Lets Eat fish food grew 1.5cm.