QUESTION 3 (15 MARKS) a) The standard strength of steel wire is required to have a mean of 1250MPa. A new process is int

[answerhappygod]

Question 3 15 Marks A The Standard Strength Of Steel Wire Is Required To Have A Mean Of 1250mpa A New Process Is Int 1 (91.72 KiB) Viewed 34 times

QUESTION 3 (15 MARKS) a) The standard strength of steel wire is required to have a mean of 1250MPa. A new process is introduced in the production of steel wire, and a random sample consisting of 25 measurements gives an average strength of 1312MPa and standard deviation, sMPa. It is assumed that the observation of steel wire strength is normally distributed. i. If the lower limit of 90% confidence interval for the true variability of the strength of steel wire made by a new process is 14436.2488, find the sample standard deviation of the strength of steel wire. (3 marks) ii. Hence, is there significant evidence that the mean strength is greater than the standard specification? Use α=0.01 level of significance. (5 marks)