Growing child: A certain girl grew steadily between the ages of 3 and 12 years, gaining 51 2 pounds each year. Let W be the girl’s weight, in pounds, as a function of her age t, in years, between the...

Growing child: A certain girl grew steadily between the ages of 3 and 12 years, gaining 51 2 pounds each year. Let W be the girl’s weight, in pounds, as a function of her age t, in years, between the ages of t = 3 and t = 12.

a. Is W a linear function or an exponential function? Be sure to explain your reasoning.

b. Write an equation of change for W.

c. Given that the girl weighed 30 pounds at age 3, find a formula for W.