The 150 oranges in a random sample from a certain supplier were weighed and the masses, X grams, were recorded. The results are summarised below.
n = 150 Σ x = 14 910 Σ x2 = 1 525 0
(i) Calculate a 99% confidence interval for the population mean of X. 
(ii) The supplier claims that the mean mass of his oranges is 100 grams. Use your answer to part (i) to explain whether this claim should be accepted. 
(iii) State briefly why the sample should be random.