6. Penshop have stores selling stationary in each of 6 towns. The population, \(P\), in tens of thousands and the monthly turnover, \(T\), in thousands of pounds for each of the shops are as recorded below.
| Town | Abberton | Bember | Claster | Deller | Edgeton | Figland |
| \(P\) (0000's) | 3.2 | 7.6 | 5.2 | 9.0 | 8.1 | 4.8 |
| T (£ 000's) | 11.1 | 12.4 | 13.3 | 19.3 | 17.9 | 11.8 |
- Represent these data on a scatter diagram with \(T\) on the verical axis.
- Which town's shop might appear to be underachieving given the populations of the towns?
- Suggest two other factors that might affect each shop's turnover.
You may assume that
$$\Sigma P = 37.9 , \quad \Sigma T = 85.8 , \quad \Sigma P ^ { 2 } = 264.69 , \quad \Sigma T ^ { 2 } = 1286 , \quad \Sigma P T = 574.25 .$$
- Find the equation of the regression line of \(T\) on \(P\).
- Estimate the monthly turnover that might be expected if a shop were opened in Gratton, a town with a population of 68000.
- Why might the management of Penshop be reluctant to use the regression line to estimate the monthly turnover they could expect if a shop were opened in Haggin, a town with a population of 172000 ?