(i) To draw the histogram, calculate the frequency density for each class interval. Frequency density is given by:

\(\text{Frequency Density} = \frac{\text{Frequency}}{\text{Class Width}}\)

Class widths: 20, 5, 5, 10, 20

Frequency densities: \(\frac{18}{20} = 0.9\), \(\frac{15}{5} = 3\), \(\frac{21}{5} = 4.2\), \(\frac{52}{10} = 5.2\), \(\frac{28}{20} = 1.4\)

Draw bars with these heights for each class interval.

(ii) Calculate the mean:

Midpoints: 30.5, 43, 48, 55.5, 70.5

Mean: \(\frac{(30.5 \times 18) + (43 \times 15) + (48 \times 21) + (55.5 \times 52) + (70.5 \times 28)}{134} = \frac{7062}{134} = 52.701 \approx 52.7\)

Calculate the variance:

\(\text{Var} = \frac{(30.5^2 \times 18) + (43^2 \times 15) + (48^2 \times 21) + (55.5^2 \times 52) + (70.5^2 \times 28)}{134} - 52.701^2\)

\(= \frac{392203.5}{134} - 52.701^2 = 149.496\)

Standard deviation: \(\sqrt{149.496} = 12.2\)