AP Statistics 4.8.B Claims from Differences in Means

Practise deciding whether a confidence interval supports a difference between population means and using its sign to identify the higher mean.

Exam points

Use whether zero lies in the interval to judge evidence for a difference between population means.
Use the sign and response-scale limits to identify which ordered mean difference is plausible.

[Maximum number: 2]

Cumulative exposure to nitrogen dioxide ( $\mathrm{NO}_{2}$ ) is a major risk factor for lung disease in tunnel construction workers. In one study, researchers compared cumulative exposure to $\mathrm{NO}_{2}$ (in parts per million per year, ppm/yr) for a random sample of drill and blast workers and for an independent random sample of concrete workers. Summary statistics are shown in the following table:
\begin{tabular}[t]{|l|l|l|l|}
\hline Tunnel Worker
Activity & Sample Size & Mean
Cumulative NO2
Exposure
(ppm/yr) & Standard
Deviation in
Cumulative $\mathbf{N O}_{\mathbf{2}}$
Exposure
(ppm/yr) \\
\hline Drill and
blast & 115 & 4.1 & 1.8 \\
\hline Concrete & 69 & 4.8 & 2.4 \\
\hline
\end{tabular}

Figure for Question 4.8.B—Justify a claim based on a confidence interval for the difference between two population means question 1 — AP Statistics

Assume conditions hold and use 95 percent confidence.

Determine whether there is evidence of a difference and justify.

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4.8.B—Justify a claim based on a confidence interval for the difference between two population means question 1