A consumer magazine contacted a random sample of 33 owners of a certain car model and asked each owner how many defects had to be corrected within the first 2 months of ownership. The average number of defects was 3.7, with a standard deviation of 1.8 defects. a) Determine a 90% confidence interval for the true mean number of defects for this car model. b) Determine a 95% confidence interval for the true mean number of defects for this car model. c) Determine a 99% confidence interval for the true mean number of defects for this car model.
A consumer magazine contacted a random sample of 33 owners of a certain car model and asked each owner how many defects had to be corrected within the first 2 months of ownership. The average number of defects was 3.7, with a standard deviation of 1.8 defects.
a) Determine a 90% confidence interval for the true
b) Determine a 95% confidence interval for the true mean number of defects for this car model.
c) Determine a 99% confidence interval for the true mean number of defects for this car model.
d) Find the length of the confidence intervals. What do you observe about width of the confidence interval as the level of confidence increases?
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