Percentage Error Area Eca391
1. **State the problem:** We need to find the percentage error in the area of a rectangle with length $11.3$ cm and width $9.23$ cm.
2. **Formula for area of a rectangle:**
$$\text{Area} = \text{length} \times \text{width}$$
3. **Calculate the area:**
$$\text{Area} = 11.3 \times 9.23 = 104.399$$ cm$^2$
4. **Percentage error in area:** When multiplying two measurements, the percentage error in the area is approximately the sum of the percentage errors in length and width.
5. **Calculate percentage errors in length and width:**
- Length $= 11.3$ cm, correct to 3 significant figures, so the absolute error is about $\pm 0.05$ cm (half of the last digit).
- Percentage error in length:
$$\frac{0.05}{11.3} \times 100 = 0.4425\%$$
- Width $= 9.23$ cm, correct to 3 significant figures, so the absolute error is about $\pm 0.005$ cm.
- Percentage error in width:
$$\frac{0.005}{9.23} \times 100 = 0.0542\%$$
6. **Sum the percentage errors to get the percentage error in area:**
$$0.4425\% + 0.0542\% = 0.4967\%$$
7. **Round to 3 significant figures:**
$$0.497\%$$
**Final answer:** The percentage error in the area is approximately $0.497\%$ correct to 3 significant figures.