Question5:

A manufacturer of car batteries claims that batteries will last on the average 3 years with a variance of 1 year. If 5 of these batteries have life times of 1.9, 2.4, 3.0 , 3.5 and 4.2 years. Construct a 95% confidence interval for variance and decide if the manufacturers claim that is valid.

[05 Marks]

Question6:

A sample of 10 networking sites for a specific month has a mean of 26.1 and a standard deviation of 4.2. Find the 99% confidence interval of the true mean.

[05 Marks]