(i) To draw the histogram, calculate the frequency density for each class interval. The class widths are 20, 10, 10, 10, 10, 15. The frequency densities are calculated as follows:

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

For 1–20: \(\frac{40}{20} = 2.0\)

For 21–30: \(\frac{34}{10} = 3.4\)

For 31–40: \(\frac{56}{10} = 5.6\)

For 41–50: \(\frac{54}{10} = 5.4\)

For 51–60: \(\frac{29}{10} = 2.9\)

For 61–75: \(\frac{21}{15} = 1.4\)

Draw the histogram with these frequency densities.

(ii) To calculate the mean, use the midpoints of each class interval:

Midpoints: 10.5, 25.5, 35.5, 45.5, 55.5, 68

Mean = \(\frac{\sum xf}{234} = \frac{8769.5}{234} = 37.5\)

To calculate the standard deviation, first find the variance:

Variance = \(\frac{\sum x^2f}{234} - \text{mean}^2\)

Standard Deviation = \(\sqrt{\text{Variance}} = 16.9\)