Split up [1, 3] into 4 subintervals:
[1, 3/2], [3/2, 2], [2, 5/2], [5/2, 3]
each with length (3 - 1)/2 = 1/2.
The right endpoints
are {3/2, 2, 5/2, 3}, which we can index by the sequence

with
.
Evaluating the function at the right endpoints gives the sampling points
, {27/4, 5, 11/4, 0}.
Then the area is approximated by
