tire manufacturer claims that the life span of its tires is 60,000 miles. Assume the life spans of the tire are normally distributed.

tire manufacturer claims that the life span of its tires is 60,000 miles. Assume the life spans of the tire are normally distributed. You selected 25 tires at random and tested them. The mean life span of the sample is 58,800 miles. The tires had a sample standard deviation, s = 600. Use the .10 level of significance.

1. Which distribution would be indicated?
2. Explain why you chose that distribution.
3. Construct a confidence interval for the mean using the above data. Use the .10 level of significance.
4. Re-compute the confidence interval if “n” is increased to 125 with the same mean and standard deviation.
5. Re-compute the confidence interval if level of significance .01 with the same mean and standard deviation with the original n.

Solutions

Expert Solution

a] t distribution would be used.

b] Because population standard deviation is unknown therefore we will use t disrtribution.

sample mean MARGIN OF ERROR

58800205.306

90% CI IS ( 58594.694 , 59005.306)

e] LEVEL OF SIGNIFICNCE =0.01

99% CI IS

orchestra answered 1 year ago

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