(a) By reading values from the given graph of $f$, use five rectangles to find a lower estimate and an upper estimate for the area under the given graph of $f$ from $x = 0$ to $x = 10$.

Lower estimate $\approx$

Upper estimate $\approx$

(b) Repeat part (a) with 10 rectangles in each case.

Lower estimate $\approx$

Upper estimate $\approx$