Someone reported a confidence interval of (1032.64, 1037.36). Given that the sample size was n= 32 and that the standard deviation was σ= 6.8, find the confidence level used by the person. Round your percentage(%) to 2 decimal places
1. Someone reported a confidence interval of (1032.64, 1037.36). Given that the
2. A certain motor is designed to spin at 3600 rpm. However, due to differences in the manufacturing process, some are faster and some are slower.
Engineers testing 20 of such motors find that the standard deviation of the rpm of the 20 tested motors is 45 rpm. Use this information to calculate the margin of error, at the 90% confidence level. Round to 1 decimal place.
3. Engineers measure the melting point under carfully controlled conditions to find the estimate of the true mean melting point of a metal. The true standard deviation of all melting points for this metal is 3.2 degrees C. How many measurements will be needed to obtain a margin of error of 0.8 degrees C with 95% confidence? Round answer up to whole number.
From the provided information,
Sample size (n) = 32
Confidence interval is (1032.64, 1037.36)
Standard deviation (σ) = 6.8
The required confidence level can be obtained as:
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