9. It is believed that it does not matter where you by your car from, whether from

company A or company B, all take the same average time until they are broken

down.

- A sample of 42 taken from company A showed an average time to breakdown of

12 years with standard deviation of 4 years.

- A sample of 51 taken from company B showed an average time to breakdown of

10 years with standard deviation of 6 years.

With a = 0.01, test if the belief is true assuming 0₁ = 0₂. [10 Marks]