The rectangles $in$ the graph below illustrate a right endpoint Riemann sum for $f(x)=\frac{x^2}{12}on$ the interval $2,6.$

The value $of$ this right endpoint Riemann sum $is5\mathrm{.}77(1),$ and this Riemann sum $isan$ overestimate $of$ the area $of$ the region enclosed $byy=f(x),$ the $x-$axis, and the vertical lines $x=2$ and $x=6.$