Tabular Estimation 2Ca70D
1. **Problem Statement:**
Estimate the area under the curve of the function $f$ given by the table:
| $x$ | 0 | 1 | 2 | 3 |
|-----|---|---|---|---|
| $f(x)$ | 2 | 3 | 5 | 4 |
using (a) Left sum, (b) Right sum, and (c) Midpoint sum with $n=3$ subintervals from $x=0$ to $x=3$.
2. **Formula and Explanation:**
- The interval length is $3 - 0 = 3$.
- Number of subintervals $n=3$, so each subinterval width is $\Delta x = \frac{3}{3} = 1$.
- **Left sum:** Use the left endpoint of each subinterval to find the height.
- **Right sum:** Use the right endpoint of each subinterval.
- **Midpoint sum:** Use the midpoint of each subinterval.
3. **Calculations:**
(a) Left sum:
$$\text{Left sum} = \Delta x \times [f(x_0) + f(x_1) + f(x_2)] = 1 \times (2 + 3 + 5) = 10$$
(b) Right sum:
$$\text{Right sum} = \Delta x \times [f(x_1) + f(x_2) + f(x_3)] = 1 \times (3 + 5 + 4) = 12$$
(c) Midpoint sum:
- Midpoints are $x=0.5, 1.5, 2.5$.
- We estimate $f(0.5)$, $f(1.5)$, and $f(2.5)$ by averaging adjacent values:
- $f(0.5) \approx \frac{f(0) + f(1)}{2} = \frac{2 + 3}{2} = 2.5$
- $f(1.5) \approx \frac{f(1) + f(2)}{2} = \frac{3 + 5}{2} = 4$
- $f(2.5) \approx \frac{f(2) + f(3)}{2} = \frac{5 + 4}{2} = 4.5$
$$\text{Midpoint sum} = \Delta x \times [2.5 + 4 + 4.5] = 1 \times 11 = 11$$
4. **Final answers:**
- Left sum estimate: $10$
- Right sum estimate: $12$
- Midpoint sum estimate: $11$