IM stuck on this can anyone plz help me i will give medal and i will fan..

Stacy is studying the sale of a particular brand of cereals from the year 1995 to 2004. She writes the following function to model the sale of the cereal S(t), in million dollars, after t years:

S(t) = t^2 + 6t + 48

Part A: What does the y-intercept of the graph of the function represents?

Part B: What is the reasonable domain of the graph of the function?

Part C: What is the average rate of change of the sale of cereal from the first year to the fourth year? Show your work.

Question

IM stuck on this can anyone plz help me i will give medal and i will fan..

Stacy is studying the sale of a particular brand of cereals from the year 1995 to 2004. She writes the following function to model the sale of the cereal S(t), in million dollars, after t years:

S(t) = t^2 + 6t + 48

Part A: What does the y-intercept of the graph of the function represents? 

Part B: What is the reasonable domain of the graph of the function?

Part C: What is the average rate of change of the sale of cereal from the first year to the fourth year? Show your work.