(i) To find the frequency density, use the formula:

\(\text{Frequency density} = \frac{\text{Frequency}}{\text{Class width}}\)

For the class 3.20 ≤ x < 3.40, the class width is \(3.40 - 3.20 = 0.20\).

Given frequency is 8, so:

\(a = \frac{8}{0.20} = 40\)

(ii) To draw the histogram:

- Use uniform linear scales from at least 2.8 to 3.4 on the x-axis and 0 to 240 on the y-axis.

- Label both axes, with 'length (m)' on the x-axis and 'frequency density' on the y-axis.

- Draw bars with the following heights based on frequency density:

• 2.80 ≤ x < 3.00: height = 85
• 3.00 ≤ x < 3.10: height = 240
• 3.10 ≤ x < 3.20: height = 190
• 3.20 ≤ x < 3.40: height = 40

- Ensure correct widths with no gaps between bars.