2. (15 marks) Suppose a company of table salt claims that the net weight of salt is at least 1 kg. But some consumers think that it is less than 1 kg. A randomly selected sample of twelve (n = 12) values gives us the following information: Exi =11.36, x? =11.56. Assume that the weight of salt in kg from this company follows a normal distribution. (a) Calculate the sample mean and sample standard deviation for these data. [5 marks] (b) Construct and interpret a 95% confidence interval for the population mean weight of salt. [4 marks] (c) Test whether the net weight of salt is less than 1 kg with significance level 1%. [6 marks]