(i) The frequency density for the interval 200 to 250 is 1.5. The width of the interval is 50. Therefore, the number of people is given by:

\(1.5 \times 50 = 75\)

(ii) The frequencies for each interval are 10, 25, 50, 75, 30. The mid-points of the intervals are 125, 162.5, 187.5, 225, 300.

Mean calculation:

\(\text{Mean} = \frac{(10 \times 125) + (25 \times 162.5) + (50 \times 187.5) + (75 \times 225) + (30 \times 300)}{190}\)

\(= \frac{40562.5}{190} = 213\)

Standard deviation calculation:

\(sd^2 = \frac{10 \times 125^2 + 25 \times 162.5^2 + 50 \times 187.5^2 + 75 \times 225^2 + 30 \times 300^2}{190} - (213)^2\)

\(sd = 46.5 \text{ or } 46.6\)

(iii) The answers are estimates because the mid-points of each interval were used instead of the raw data.