9709 P61 - Nov 2017 - Q4
2426
The ages of a group of 12 people at an Art class have mean 48.7 years and standard deviation 7.65 years. The ages of a group of 7 people at another Art class have mean 38.1 years and standard deviation 4.2 years.\n\n(i) Find the mean age of all 19 people.\n\n(ii) The individual ages in years of people in the first Art class are denoted by \(x\) and those in the second Art class by \(y\). By first finding \(\Sigma x^2\) and \(\Sigma y^2\), find the standard deviation of the ages of all 19 people.
