5 (a) The score of fluid mechanics test has a normal distribution with mean 85 if given the standard deviation of sample

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5 A The Score Of Fluid Mechanics Test Has A Normal Distribution With Mean 85 If Given The Standard Deviation Of Sample 1 (62.19 KiB) Viewed 33 times

5 (a) The score of fluid mechanics test has a normal distribution with mean 85 if given the standard deviation of sample is nine. The lecturer claimed that if the student learned more than eight hours per week, the mean score would be different than 85 . A test was given to a random sample of 60 candidates with the mean score was 88 . (i) Rephrase the null and alternative hypotheses. (2 marks) (ii) Identify the type I error and type II error that correspond to the hypothesis above. (2 marks) (iii) Test the claim at 10% level of significance. (6 marks) (b) A production manager would like to know the precision of the operator producing the product. The product thickness is assumed to be normally distributed, with standard deviation of 2 mm. How large a sample must be selected if he wants to be 99% confident of finding whether the true mean differs from the sample mean by 0.25 mm.