3. The petrol station A - J, which are situated in areas of similar traffic density are ranked firstly according to quality of service, secondly according to the size of the forecourt and thirdly according to the price of the petrol sold. Rank 1 indicates best service, largest forecourt and lowest price. The results including the average weekly petrol sales are given below: Station Quality of Forecourt Petrol Sales service size price ('000 of gallons) 4? 2O 23 36 36 31 33 28 42 24 (a) Carry out calculations to decide whether price of petrol or quality of service is likely to be more important factor in determining the volume of petrol sales, or whether neither appears to important