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A new type of thread is being tested for strength. 16 pieces of the thread are...

A new type of thread is being tested for strength. 16 pieces of the thread are tested. The sample is found to have an average tensile strength of 78.3 kg with a standard deviation of 8 kg. (a) Construct a 95% confidence interval for the tensile strength of the new thread. (b) What do you have to assume about the population and about the sample in order for this to be a valid confidence interval?

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Answer #1

a) Let denotes the mean tensile strength of the new thread.

b) Assumption : tensile strength is normally distributed.

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