Question
In: Statistics and Probability
) A thread manufacturer test a sample of eight lengths of a certain type of thread...
) A thread manufacturer test a sample of eight lengths of a certain type of thread made of blended materials and obtains a mean strength of 8.2 lb with standard deviation 0.06 lb. Assuming tensile strengths are normally distributed, construct a 90% confidence interval for the mean tensile strength of this thread.
Solutions
Expert Solution
n = sample size = 8
s = sample standard deviation = 0.06
Formula for confidence interval
E means margin of error.
C = level of confidence = 0.900 ( We converted 90 % in to decimal )
n - 1 = degrees of freedom (d .f ) = 8-1 = 7
We look for row headed df = 7 and column headed c = 0.900
We use formula of confidence interval
90% confidence interval for the mean tensile strength of this thread is
Final answer :-
90% confidence interval for the mean tensile strength of this thread is
orchestra answered 1 year agoRelated Solutions
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