Three Rectangles of Distance

A delivery drone flies in a straight line. Its speed is modelled by

$v(t) = t^2 + 2t$

where $t$ is the time in seconds and $v(t)$ is measured in metres per second.

You want to estimate the distance the drone covers between $t = 1$ and $t = 7$ seconds — that is, the area sitting under this speed curve across that interval.

Chop the interval $[1, 7]$ into $n = 3$ subintervals of equal width, and build a Riemann sum in which the height of each rectangle is the drone's speed at the right endpoint of that rectangle's own subinterval.

What distance estimate, in metres, does this right-endpoint Riemann sum produce? Your answer is a whole number.