Question 1 a) A random sample of 41 glass sheets is obtained and their thicknesses are...

Question 1
a) A random sample of 41 glass sheets is obtained and their thicknesses are measured.The sample mean is found to be 3.04 mm with standard deviation 0.124 mm.Construct a 90% confidence interval for the mean glass thickness.

b) The resilient moduli of clay mixture is found to be normally distributed with mean . A sample of 10 clay mixture is selected and the resilient moduli are measured as
follow:
19.6 19.4 19.9 19.3 20.1 19.0 19.5 19.4 20.3 19.7
Construct a 99% confidence interval for the mean resilient moduli of clay mixture.

c) A company advertises that its electric motors provide an efficiency that is at least 25% higher than the industry norm. A consumer interest group ran an experiment with a
sample of 35 machines for which the increases in efficiency over the industry norm had a sample mean of 22.3% and the sample standard deviation of 8.72%. Perform a hypothesis testing at 5% significance level to test whether the company’s claim is false.

Expert Solution

orchestra answered 1 year ago

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