Left and right Riemann sums Complete the following steps for the given function, interval, and value of $n.$
a. Sketch the graph of the function on the given interval.
b. Calculate $\Delta x$ and the grid points $x_{0}, x_{1}, \ldots, x_{n^{*}}.$
c. Illustrate the left and right Riemann sums. Then determine which Riemann sum underestimates and which sum overestimates the area under the curve.
d. Calculate the left and right Riemann sums.
$$f(x)=e^{x / 2} \text { on }[1,4] ; n=6$$