(i) We know that \(\Sigma(x-a) = -73.2\). Since there are 24 observations, the mean of \(x-a\) is \(\frac{-73.2}{24} = -3.05\). Given that the mean of \(x\) is 8.95, we have:

\(a = 8.95 + 3.05 = 12\)

(ii) The standard deviation is calculated using:

\(\text{Standard deviation} = \sqrt{\frac{\Sigma(x-a)^2}{24} - (\text{mean of } x-a)^2}\)

\(= \sqrt{\frac{2115}{24} - (-3.05)^2}\)

\(= \sqrt{88.125 - 9.3025}\)

\(= \sqrt{78.8225}\)

\(= 8.88\)