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2. In a study on low-back pain (LBP), a random sample of 31 workers who suffer...

2. In a study on low-back pain (LBP), a random sample of 31 workers who suffer from LBP were tested for lateral range of motion (in degrees). The average was found to be 88.3o and sample standard deviation 7.8o. A similar sample of 28 workers who did not suffer from LBP was found to have an average lateral range of motion of 91.5o and sample standard deviation 5.5o. Compute a 90% confidence interval for the difference in the true mean lateral range of motion for the two populations;

3. In the calculation of a 95% confidence interval for the mean of a population, based on a random sample of 15 measurements, it is necessary to use a percentile value from a t-distribution on:

95 degrees of freedom

14 degrees of freedom

15 degrees of freedom

5 degrees of freedom

16 degrees of freedom

Math   Statistics-And-Probability   
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