Step 1:
The lower sum is the sum over the 4 partitions of the
Step 2:
The upper sum is the sum over the 4 partitions of the
Step 3:
Trapezoid rule will take the line that joins the upper and the lower values in each partition ( average of the upper and lower) , resulting in a sum that is between the upper sum and the lower sum.
Final answer
Lower sum < trapezoid rule < upper sum