Statistics questin

QUESTION ONE

i.What is the difference between point estimation and interval estimation? (2 Marks)

ii.A sample of 8 observations has been taken from a population in which the random variable is normally distributed. The sample mean is 25 and the sample standard deviation is 5. Determine a 95% confidence interval for the population mean. (5 marks)

• The mean life of a sample of 200 light tubes produced by a company is found to be 3160 hours with a standard deviation of 180 hours. Test the hypothesis that the mean lifetime of the tubes by the company is 3200 hours. (5 Marks)

iv.A sample of 20 measurements of the diameter of a sphere gave a mean 4.38 inches and standard deviation of 0.06 inches find

• 95% confidence limit to the actual diameter (4 marks)
• 99% confidence limit to the actual diameter. (4 marks)