Let g be a function with values given by the table below.
Use a left-hand sum with 3 sub-intervals to estimate the area between the graph of g and the x-axis on the interval
Breaking the interval [0,12] into 3 sub-intervals gives us 3 sub-intervals of size 4. We need the following values of g, which we find by looking them up in the table:
We add these values and multiply by the width of a sub-interval: