Final answer:
Without knowing how much water is needed for one batch of green slime, we cannot confirm if 3 cups of water are adequate for a double recipe.
Step-by-step explanation:
To determine if 3 cups of water is enough for Chery to make a double recipe of green slime for a class project, we must first know how much water is required for a single batch. Since the provided information does not specify the amount of water needed for one batch, we cannot calculate the total amount needed for a double batch. Therefore, we cannot definitively say whether 3 cups of water are sufficient without additional information on the water requirement for a single batch of the green slime recipe.