The Upper Sum S(n) is shaded in Blue.
The Lower Sum s(n) is shaded in Brown.

Question: How are the heights of each rectangle found for the Upper Sum ?
Question 2: How are the heights of each rectangle found for the Lower Sum?
Question 3: Give a convincing explanation about why the area of the region bounded by f(x) and the x-axis between x = 1 and x= 3.2 is between 4.53 and 4.76