4. The owner of a mobile burger-bar believes that hot weather reduces his sales. To investigate the effect on his business he collected data on his daily sales, \(\pounds P\), and the maximum temperature, \(T ^ { \circ } \mathrm { C }\), on each of 20 days. He then coded the data, using \(x = T - 20\) and \(y = P - 300\), and calculated the summary statistics given below. $$\Sigma x = 57 , \quad \Sigma y = 2222 , \quad \Sigma x ^ { 2 } = 401 , \quad \Sigma y ^ { 2 } = 305576 , \quad \Sigma x y = 3871 .$$

1. Find an equation of the regression line of \(P\) on \(T\). The owner of the bar doesn't believe it is profitable for him to run the bar if he takes less than \(\pounds 460\) in a day.
2. According to your regression line at what maximum daily temperature, to the nearest degree Celsius, does it become unprofitable for him to run the bar?
   (3 marks)