AP Statistics 4.7.A Choosing a Two-Sample t-Interval

Practise recognising when two independent groups require a two-sample t-interval and defining the parameter as a difference between population means.

Exam points

Choose a two-sample t-interval when independent groups provide quantitative response data.
Define the parameter as the difference in population means for the response and populations in context.

[Maximum number: 1]

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 4.7.A—Identify an appropriate confidence interval procedure including the parameter for the difference between two… question 1 — AP Statistics

Identify the appropriate inference procedure.

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4.7.A—Identify an appropriate confidence interval procedure including the parameter for the difference between two… question 1