CIE A level Math -Probability & Statistics 2: 6.4 Sampling and estimation : calculate unbiased estimates: Exam Style Questions Paper 6


 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. [6]

     (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. [1]

     (iii) State briefly why the sample should be random. [1]