Two types of new cars produced in India are tested for petrol mileage. One group consisting of 36 cars averaged 14kms. per litre. While the other group consisting of 72 cars averaged 12.5 kms per litre.
(a) What test statistic is appropriate, if
(b) Test, Whether there exists a significant difference in the petrol consumption of these two types of cars. (Use alpha=0.01)