Find three Confidence Interval examples from either the “real-world” or from industry

Part A:

Find three Confidence Interval examples from either the “real-world” or from industry. Think critically and discuss in detail if:

1)    You believe that these examples were good or bad representations of CI’s and 2) you feel they were helpful or hurtful to argument being made. When you find these sources, they must be from reputable sources and appropriately cited. In addition to your discussion, please attach a copy of these CI’s and any associated work.

Part B:

The Insurance Institute for Highway Safety routinely conducts crash tests on vehicles to determine the cost of repairs. In four crashes of a Chevy Cavalier at 5 miles per hour, the institute found the cost of repairs to be $480, $246, $1251, and $192.

Treat these data a simple random sample of four crashes, and answer the following questions, assuming that σ = $280.

1)      Use the data to compute a point estimate for the population mean cost repairs on a Chevy Cavalier.

2)      Because the sample size is small, we must verify that cost is approximately normally distributed and that the sample does not contain any outliers. Make and analyze the normal probability plot and boxplot. Based on these plots, can you assume that cost is approximately normal?

3)      Construct a 95% confidence interval for the cost of repairs. Interpret this interval.

4)      Construct a 90% confidence interval for the cost of repairs. Interpret this interval.

5)      What happened to the width of the interval when the level of confidence decreased? Explain why this result is reasonable.