Question 1:
A test of the breaking strengths of 6 wires manufactured by a company demonstrated a mean breaking strength of 7750 N/mm2 and a standard deviation of 145 N/mm2, but the manufacturer opined a mean breaking strength of 8000 N/mm2. Test the hypothesis whether the mean breaking strength is less than 8000 N/mm2 or not at the significance level of (i) 5% and (ii) 1%?
又係統計學, 救我 0
2007-04-03 10:26 am
回答 (1)
2007-04-03 5:43 pm
✔ 最佳答案
n=6, sample mean=7750, standard deviation=145null hypothesis: actual mean=8000
alternative: actual mean < 8000
Z = (sample mean - actual mean) / [standard deviation/sqrt(n)]
Z = (7750-8000) / [145/sqrt(6)]
= -250/ 59.196
= -4.22 ( < -1.645 for 5% and < -2.325 for 1%)
reject null hypothesis in both cases
so we "accept" the alternative, that is, the mean is less than 8000N/mm2.
p.s. Type I error exists.
參考: myself
收錄日期: 2021-04-13 14:13:58
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070403000051KK00308