A model that represents the data is given by $y=\frac{63.6+0.97 t}{1+0.01 t}, \quad 0 \leq t \leq 70$
where $t$ is the time in years, with $t=0$ corresponding to 1940
(a) Use a graphing utility to graph the data from the table above and the model in the same viewing window. How well does the model fit the data? Explain.
(b) Find the $y$ -intercept of the graph of the model. What does it represent in the context of the problem?
(c) Use the zoom and trace features of the graphing utility to determine the year when the life expectancy was $70.1 .$ Verify your answer algebraically.
(d) Determine the life expectancy in 1978 both graphically and algebraically.