Actually, the statement that "6 cups of sugar yields 4 dozen cookies" contradicts the previous statements. According to the given information, 4/6 cups of sugar yields 1 dozen cookies, 4 sixths cups of sugar yields 1 dozen cookies, and 4 cups of sugar yields 6 dozen cookies. Therefore, it is more accurate to say that 4 cups of sugar yields 6 dozen cookies, not 6 cups of sugar.
