(i) We know that 15.5% of desks have a height greater than 70 cm. This corresponds to a z-score of approximately 1.015 (from standard normal distribution tables).

Using the standardization formula:

\(z = \frac{X - \mu}{\sigma}\)

Substitute the known values:

\(1.015 = \frac{70 - 69}{\sigma}\)

Solve for \(\sigma\):

\(\sigma = \frac{1}{1.015} = 0.985\)

(ii) Jodu's knees are at 58 cm, and they need to be at least 9 cm below the desk top, so the desk height must be greater than 67 cm (58 + 9).

Standardize 67 cm:

\(P(>67) = P\left( z > \frac{67 - 69}{0.985} \right)\)

\(= P(z > -2.03)\)

From standard normal distribution tables, \(P(z > -2.03) = 0.9788\).

Estimate the number of comfortable desks:

\(300 \times 0.9788 = 293.64\)

Therefore, approximately 293 desks are comfortable for Jodu.