Metal castings are manufactured on two production lines, A and B. Their masses are distributed normally with μA andμB and standard deviations 0.18kg and 0.21 kg respectively. A random sample of 8 casting from production line A has mean mass 5.43kg and a random sample of 12 casting from production line B has means 5.58kg . 問題 : (a) Calculate a 98% confidence interval for μA andμB.(b) State, giving a reason, whether there is a difference between the means at 2% significance level.(c) 呢題點解用z-test而唔係用t-test 去計呢..? 答(a) & (b) 時, 應該注意咩地方? 以咩方法去計呢條數呢..? Thanks!!!! ^ u ^
更新1:
唔該晒你丫, 解釋得好詳盡, thanks!~~ ^u^