You want to test whether the average fuel consumption (kilometers per litre) differ between the types of car engine. A sample of 15 vehicles was taken and data on fuel consumption for different types of car engine are Diesel 12 16 Car Engine Petrol 10 10 13 8 10 Standard deviation = 1.789 14 Hybrid 14 16 16 13 18 Standard deviation = 1.949 17 11 Standard deviation = 2.55 State the following: (a) Grand mean (b) Amount of variation that is attributable to the types of car engine