- A long distance lorry driver recorded the distance travelled, \(m\) miles, and the amount of fuel used, \(f\) litres, each day. Summarised below are data from the driver's records for a random sample of 8 days.
The data are coded such that \(x = m - 250\) and \(y = f - 100\).
$$\Sigma x = 130 \quad \Sigma y = 48 \quad \Sigma x y = 8880 \quad \mathrm {~S} _ { x x } = 20487.5$$
- Find the equation of the regression line of \(y\) on \(x\) in the form \(y = a + b x\).
- Hence find the equation of the regression line of \(f\) on \(m\).
- Predict the amount of fuel used on a journey of 235 miles.