Total Weight
1. **State the problem:** We need to estimate the total weight of all the suitcases using the histogram data.
2. **Understand the histogram:** The histogram shows frequency density on the y-axis and weight intervals on the x-axis.
3. **Calculate the frequency for each weight interval:** Frequency = frequency density \( \times \) class width.
- For 1 to 3 kg: height = 3, width = 3 - 1 = 2, frequency = 3 \times 2 = 6
- For 3 to 4 kg: height = 5, width = 4 - 3 = 1, frequency = 5 \times 1 = 5
- For 4 to 7 kg: height = 1, width = 7 - 4 = 3, frequency = 1 \times 3 = 3
4. **Estimate the midpoint weight for each interval:**
- 1 to 3 kg midpoint = \( \frac{1+3}{2} = 2 \)
- 3 to 4 kg midpoint = \( \frac{3+4}{2} = 3.5 \)
- 4 to 7 kg midpoint = \( \frac{4+7}{2} = 5.5 \)
5. **Calculate the total weight estimate for each interval:** Total weight = frequency \( \times \) midpoint
- 1 to 3 kg: 6 \times 2 = 12
- 3 to 4 kg: 5 \times 3.5 = 17.5
- 4 to 7 kg: 3 \times 5.5 = 16.5
6. **Sum all total weights:**
$$12 + 17.5 + 16.5 = 46$$
7. **Final answer:** The estimated total weight of all the suitcases is **46.0 kg** (to 1 decimal place).