Answer
(a) (i) $87$, (ii) $71$
(b) overestimate
(c) underestimate
Work Step by Step
(a) See figure for the configuration of rectangles.
(i) $L_6=2(9+8.8+8.3+7.4+6+4)=87$
(ii) $R_6=2(8.8+8.3+7.4+6+4+1)=71$
(b) We can see that $L_6$ is an overestimate of the true area.
(c) We can see that $R_6$ is an underestimate of the true area.
