Answer
$f\left( x \right)=a{{x}^{2}}+bx+c,a>0$
Work Step by Step
In the provided bar graph between average numbers of annual visits per person to ages, it is observed that the data points fall from 0-15 to 16-24 and then rise from 16-24 to 66 and older. The graph appear to represent a quadratic function that opens upward.
Thus, the quadratic function $f\left( x \right)=a{{x}^{2}}+bx+c,a>0$ can be used to model the data.
