QUESTION 4 The average breaking strength of a metal rod is specified to be 10,000 kg. To test this, a random sample of 49 rods were taken and tested. The mean and standard deviation obtained was 9,990kg and 30kg respectively. At 5% level of significance, is there evidence that this metal rod is below its specified breaking strength? [25 marks] X-| Z=* Critical value: z= 1.96 (two tails) z= 1.64 (one tail)