Joseph's grandparents get him a puppy for his thirteenth birthday, and he names the puppy Bailey. Joseph does a good job taking care of Bailey, and she's growing so fast! When Bailey is 1 month old, she weighs 3 pounds. When she is 3 months old, she weighs 6 pounds. In this relationship, x represents Bailey's age (in months), and y represents her weight (in pounds). Explain why this is not a proportional relationship.