Answer:
The average age was minimum at 1954 and the average age is 25.5.
Step-by-step explanation:
The given quadratic function is
[tex]f(x)=0.0039x^2-0.42x+36.79[/tex]
It models the median, or average, age, y, at which men were first married x years after 1900.
In the above equation leading coefficient is positive, so it is an upward parabola and vertex of an upward parabola, is point of minima.
We need to find the year in which the average age was at a minimum.
If a quadratic polynomial is [tex]f(x)=ax^2+bx+c[/tex], then vertex is
[tex]Vertex=(-\dfrac{b}{2a},f(-\dfrac{b}{2a}))[/tex]
[tex]-\dfrac{b}{2a}=-\dfrac{(-0.42)}{2(0.0039)}=53.846153\approx 54[/tex]
54 years after 1900 is
[tex]1900+54=1954[/tex]
Substitute x=54 in the given function.
[tex]f(54)=0.0039(54)^2-0.42(54)+36.79=25.4824\approx 25.5[/tex]
Therefore, the average age was minimum at 1954 and the average age is 25.5.
