Scrubbers a Factory Recently Installed New Pollution Control Equipment ("Scrubbers")

Essay

Scrubbers A factory recently installed new pollution control equipment ("scrubbers") on its smokestacks in hopes of reducing air pollution levels at a nearby national park. Randomly timed measurements of sulfate levels (in micrograms per cubic meter) were taken before (Set C1) and after (Set C₂) the installation. We believe that measurements of sulfate levels are normally distributed. Write a complete conclusion about the effectiveness of these scrubbers based on the statistical software printout shown below. $\begin{array}{llllllllllllll}\text { SET C1 } & 10.0 & 8.0 & 8.0 & 7.0 & 6.0 & 9.0 & 11.5 & 8.0 & 9.5 & 7.5 & 5.0 & 10.0 \\\text { SET C2 } & 5.0 & 7.0 & 1.0 & 9.0 & 1.5 & 5.0 & 2.5 & 4.0 & 9.0 & 6.0 & & &\end{array}$

$\text { Two Sample T for C1 vs C2 }$
$\begin{array}{lllll} & \mathrm{N} & \text { Mean } & \text { StDev } & \text { SEMean } \\\mathrm{C} 1 & 12 & 8.29 & 1.83 & 0.53 \\\mathrm{C} 2 & 10 & 5.00 & 2.84 & 0.90\end{array}$
$95 \% \mathrm{Cl} \text { for mu1 - mu2: }(1.20,5.38)$
$\text { T-Test } \mathrm{mu1}=\text { mu2 (vs. not }=\text { ): } \quad T=3.29 \quad \mathrm{P}=0.0037 \quad \mathrm{DF}=20$