Question

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.​

Answer 1

We know that the statement•P( -1.96δ <µ< +1.96δ )=0.95 is correct, while the statement P(140<µ<160)=0.95 is not correct. Explain why the latter is erroneous?•Some guidelines….xxxxx117

Z values for various confdence levels•99.73% 3.00•99% 2.58•98% 2.33•96% 2.05•