The students in Mr. Young's class are making lemonade for parents night. They decided to use 3 cups of water to 1 cup of lemon juice. They show a picture on the side and it shows: that there are 1 yellow which stands for lemon juice and there are 3 red which stands for water. The ratio of cups of water to cups of lemon juice is 3 to 1. The ratio of juice to water is 1 to 3.