1. Two variables \(x\) and \(y\) are such that, for a sample of ten pairs of values,

$$\sum x = 104 \cdot 5 , \quad \sum y = 113 \cdot 6 , \quad \sum x ^ { 2 } = 1954 \cdot 1 , \sum y ^ { 2 } = 2100 \cdot 6 .$$ The regression line of \(x\) on \(y\) has gradient 0.8 . Find

1. \(\sum x y\),
2. the equation of the regression line of \(y\) on \(x\),
3. the product moment correlation coefficient between \(y\) and \(x\).
4. Describe the kind of correlation indicated by your answer to (c).