STA 301 Module 8 In-Class Activity: Introduction to Confidence Intervals
Part 1: Confidence Interval for One Population Mean
The following represent the length of life, in years (measured to the nearest tenth), of a simple random sample of 30 fuel pumps.
2.0 3.0 0.3 3.3 1.3 0.4 0.2 6.0 5.5 6.5 0.2 2.3 1.5 4.0 5.9 1.8 4.7 0.7 4.5 0.3 1.5 0.5 2.5 5.0 1.0 6.0 5.6 6.0 1.2 0.2
Source: Walpole, R.E., Myers, R.H., Myers, S.L., & Ye, K. (2012). Probability & Statistics for Engineers & Scientists. Boston, MA: Pearson.
Copy and paste this code to enter the data into R:
lengthoflife = c(2.0, 3.0, 0.3, 3.3, 1.3, 0.4, 0.2, 6.0, 5.5, 6.5, 0.2, 2.3, 1.5, 4.0, 5.9, 1.8, 4.7, 0.7, 4.5, 0.3, 1.5, 0.5, 2.5, 5.0, 1.0, 6.0, 5.6, 6.0, 1.2, 0.2)
Note: This data is posted on the Module 8 page on Canvas.
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Using RStudio, construct a normal quantile-quantile plot of this data. Discuss your findings.
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Discuss the assumptions that must be satisfied in order to construct a confidence interval for the true mean length of life (in years) of a fuel pump.
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Using RStudio, construct and interpret a 90% confidence interval for the true mean length of life (in years) of a fuel pump.
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Part 2: Confidence Interval for One Population Proportion
A geneticist is interested in the true proportion of African males who have a certain minor blood disorder. In a random sample of 100 African males, 24 are found to be afflicted.
Source: Walpole, R.E., Myers, R.H., Myers, S.L., & Ye, K. (2012). Probability & Statistics for Engineers & Scientists. Boston, MA: Pearson.
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Using RStudio, construct and interpret a 99% confidence interval for the true proportion of African males who have a certain minor blood disorder.
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Find the margin of error associated with using this sample to construct a 99% confidence interval for the true proportion of African males who have a certain minor blood disorder.
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SAMPLE ASSIGNMENT
