Chapter 11 - Quadratic Functions and Equations - 11.8 Problem Solving and Quadratic Functions - 11.8 Exercise Set - Page 756: 34

$f\left( x \right)=a{{x}^{2}}+bx+c,a<0$

In the provided bar graph between births per 1000 women to age in years, it is observed that the data points rise from age 16 to 27 and then fall from age 27 to 42. The graph appears to represent a quadratic function that open downwards. Thus, the quadratic function $f\left( x \right)=a{{x}^{2}}+bx+c,a<0$ can be used to model the data.