91Ó°ÊÓ

The article "Exhaust Emissions from Four-Stroke Lawn Mower Engines" (J. of the Air and Water Mgmnt. Assoc., 1997: 945-952) reported data from a study in which both a baseline gasoline mixture and a reformulated gasoline were used. Consider the following observations on age \((\mathrm{yr})\) and \(\mathrm{NO}_{x}\) emissions \((\mathrm{g} / \mathrm{kWh})\) : \(\begin{array}{lccccc}\text { Engine } & 1 & 2 & 3 & 4 & 5 \\ \text { Age } & 0 & 0 & 2 & 11 & 7 \\ \text { Baseline } & 1.72 & 4.38 & 4.06 & 1.26 & 5.31 \\\ \text { Reformulated } & 1.88 & 5.93 & 5.54 & 2.67 & 6.53 \\ \text { Engine } & 6 & 7 & 8 & 9 & 10 \\ \text { Age } & 16 & 9 & 0 & 12 & 4 \\\ \text { Baseline } & .57 & 3.37 & 3.44 & .74 & 1.24 \\ \text { Reformulated } & .74 & 4.94 & 4.89 & .69 & 1.42\end{array}\) Construct scatterplots of \(\mathrm{NO}_{x}\) emissions versus age. What appears to be the nature of the relationship between these two variables?

Step by step solution

01

Organize the Data

First, we list the age and corresponding \( \mathrm{NO}_x \) emissions for both baseline and reformulated gasoline.For *Baseline*:- Ages: 0, 0, 2, 11, 7, 16, 9, 0, 12, 4- \( \mathrm{NO}_x \) emissions: 1.72, 4.38, 4.06, 1.26, 5.31, 0.57, 3.37, 3.44, 0.74, 1.24For *Reformulated*:- Ages: 0, 0, 2, 11, 7, 16, 9, 0, 12, 4- \( \mathrm{NO}_x \) emissions: 1.88, 5.93, 5.54, 2.67, 6.53, 0.74, 4.94, 4.89, 0.69, 1.42.

02

Prepare the Plot Areas

For each gasoline type, set up two coordinate systems for plotting with age on the x-axis and \( \mathrm{NO}_x \) emissions on the y-axis. Use two separate graph areas or windows if possible for clarity.

03

Plot Baseline Gasoline Data

On the first graph, plot each pair of age and \( \mathrm{NO}_x \) emissions from the baseline data. For instance, plot (0, 1.72), (0, 4.38), ..., (4, 1.24). Ensure all points are clearly marked and scale the axes appropriately.

04

Plot Reformulated Gasoline Data

On the second graph, plot each pair of age and \( \mathrm{NO}_x \) emissions from the reformulated data. For instance, plot (0, 1.88), (0, 5.93), ..., (4, 1.42). Make sure all points are clear on the graph.

05

Assess the Relationship

Observe the scatterplots you've created. Look for any trend or pattern, such as an increase or decrease in \( \mathrm{NO}_x \) emissions with engine age, or clusters of data points.

Unlock Step-by-Step Solutions & Ace Your Exams!

• Full Textbook Solutions

  Get detailed explanations and key concepts

• Unlimited Al creation

  Al flashcards, explanations, exams and more...

• Ads-free access

  To over 500 millions flashcards

• Money-back guarantee

  We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

NOx Emissions

Nitrogen oxides, commonly referred to as NOx, are significant pollutants produced by engines. These emissions are composed of nitrous oxide (NO) and nitrogen dioxide (NO2). NOx emissions are noteworthy because they can contribute to both environmental and health problems.

When fuel combusts in an engine, the heat causes nitrogen and oxygen present in the air to combine, forming NOx. Several factors can influence NOx emission levels:

• Type of fuel used
• Efficiency of the combustion process
• Engine age and condition

The goal is often to reduce NOx emissions as they can lead to the formation of smog and acid rain, impacting both the environment and human health.

Gasoline Formulation

Gasoline formulations can significantly affect engine performance and emissions. In the study mentioned, two different gasoline types were used: baseline gasoline and reformulated gasoline. Reformulated gasoline is designed to burn cleaner than traditional gasoline, thereby reducing emissions.

Key differences between the two include:

• Oxygenated additives are more common in reformulated gasoline, boosting combustion efficiency.
• Reformulated gasoline generally has fewer volatile organic compounds (VOCs), which contribute to pollution.
• It often meets stringent environmental regulations, aiming to reduce the release of harmful gases including NOx.

By comparing these two formulations, one can determine which fuel type helps in minimizing pollutants while still maintaining vehicle efficiency.

Engine Age

As engines get older, their mechanisms may not operate as efficiently as they once did, potentially leading to increased emissions. In the exercise, engine age is a critical factor analyzed in conjunction with NOx emissions, especially with the data provided.

There can be several reasons for this relationship:

• Older engines may have worn components that decrease fuel efficiency.
• Maintenance practices, or lack thereof, over time play a significant role in performance.
• Technological advances in newer engines could result in reduced emissions compared to older models.

Therefore, understanding how engine age influences emissions can lead to better maintenance practices and informed decisions about when to replace older engines with newer, more efficient models.

Data Visualization

Scatterplot analysis is a powerful tool in data visualization, especially useful for identifying relationships between two variables. In this exercise, scatterplots were constructed for NOx emissions against engine age for both types of gasoline.

Creating scatterplots involves:

• Selecting the appropriate data pairs, such as age (x-axis) and NOx emissions (y-axis).
• Marking each data point so patterns become visible, such as clustering or trends.
• Using different colors or markers to distinguish between baseline and reformulated gasoline data for clarity.

Scatterplots help visualize patterns, trends, and outliers in the data, providing qualitative insights into how closely related the variables are, and if one might be affecting the other. This type of analysis is crucial for interpreting the impact of different fuel types and engine ages on emissions.