It has been found from experience that the mean breaking strength of a particular brand of thread is 9.63N with a standard deviation of 1.40N. Recently a sample if 36 pieces of thread showed a mean breaking strength of 8.93 N. Can we conclude that the thread has become inferior.
Answers
It has been found from experience that the mean breaking strength of a particular brand of thread is 9.63N with a standard deviation of 1.40N. Recently a sample if 36 pieces of thread showed a mean breaking strength of 8.93 N. Can we conclude that the thread has become inferior.
Step-by-step explanation:
We know that the following statement •P( -1.96δ <µ< +1.96δ )=0.95 is correct, while the statement P(140<µ<160)=0.95 is incorrect.
Z values for various confidence levels•99.73% 3.00•99% 2.58•98% 2.33•96%
For similar questions check out https://brainly.in/question/17920169
Answer: 1.57
Step-by-step explanation:
Using Z table, are
The p-value is p = 0.001, P(Z<=-3.091)= 0.001,since p=0.001<0.05, it is concluded that the null hypothesis is rejected.
It is concluded that the null hypothesis Ho is rejected. Therefore, there is enough evidence to claim that the population mean μ is less than 9.72, at the 0.05 significance level.