9 A researcher records a random sample of \(n\) pairs of values of \(( x , y )\), giving the following summarised data.
$$\Sigma x = 24 \quad \Sigma x ^ { 2 } = 160 \quad \Sigma y = 34 \quad \Sigma y ^ { 2 } = 324 \quad \Sigma x y = 192$$
The gradient of the regression line of \(y\) on \(x\) is \(- \frac { 3 } { 4 }\). Find
- the value of \(n\),
- the equation of the regression line of \(x\) on \(y\) in the form \(x = A y + B\), where \(A\) and \(B\) are constants to be determined,
- the product moment correlation coefficient.
Another researcher records the same data in the form \(\left( x ^ { \prime } , y ^ { \prime } \right)\), where \(x ^ { \prime } = \frac { x } { k } , y ^ { \prime } = \frac { y } { k }\) and \(k\) is a constant.
Without further calculation, state the equation of the regression line of \(x ^ { \prime }\) on \(y ^ { \prime }\).