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Assume that both sets of welds are random samples from normal populations. A sample of 6...

Assume that both sets of welds are random samples from normal populations. A sample of 6 welds of one type had an average ultimate testing strength of 83.2 (ksi) and a standard deviation 5.2. A sample of 10 welds of another type had an average strength of 71.3 and a standard deviation of 3.1.

Find a 95% confidence interval for the difference between the mean strengths of the two types of welds.

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