5. [-/2 Points] The circumference of a tree trunk at different heights above the ground is given in the table below. Assume that all horizontal cross-sections of the tree are circles and that the circumference is decreasing from the base of the tree to the top of the tree. Height (inches) 0 20 40 60 80 Circumference (inches) 30 26 20 12 4 (a) What is an upper estimate of the volume of the tree from the ground to a height of 20 inches? Give an exact answer. in3 (b) What is an upper estimate of the total volume of the tree? Use N = 4. Give an exact answer. 3 in Submit