The average rate of change is given by the final weight minus the initial weight divided by the final time minus the initial time:
[tex]\frac{63-12}{6-0}=\frac{51}{6}=8.5\text{ }\frac{ounces}{months}[/tex]
This mean that the a puppy tends to acquire around 8.5 ounces per month during its first six months of life
