(i) To find the mean age of all 32 members, calculate the total age of all members and divide by the total number of members:

\(\text{Total age of Juniors} = 15.5 \times 12 = 186\)

\(\text{Total age of Seniors} = 910\)

\(\text{Total age of all members} = 186 + 910 = 1096\)

\(\text{Mean age} = \frac{1096}{32} = 34.25 \text{ years}\)

\((ii) To find the standard deviation of all 32 members, first find the variance:\)

For Juniors, \(\text{variance} = \frac{\Sigma x^2}{12} - 15.5^2 = 1.2^2\)

\(\Sigma x^2 = 2900.28\)

For the whole group:

\(\Sigma z^2 = \Sigma x^2 + \Sigma y^2 = 2900.28 + 42850 = 45750\)

\(\text{Variance} = \frac{45750}{32} - (34.25)^2 = 256.63\)

\(\text{Standard deviation} = \sqrt{256.63} = 16.0 \text{ years}\)