Test the hypothesis that the average content of containers of a particular lubricant is 10 liters if the contents of a random sample of 10 containers are 10.2, 9.7, 10.1, 10.3, 10.1, 9.8, 9.9, 10.4, 10.3 and 9.8 liters. use a 0.01 level of significance and assume that the distribution of contents is normal (also check if that assumption is reasonable). find a 99% confidence interval for the mean content level.