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In 2012 in the United States, most electricity was generated from coal ( \(37 \%\) ), natural gas ( \(30 \%\) ), or nuclear power plants (19\%). Hydropower accounted for \(7 \%\) of the total electricity produced; other renewable sources such as wind or solar power accounted for \(5 \% .\) Other nonrenewable sources (such as petroleum) made up the remaining \(2 \%\). (Source: http://www.eia.gov/ electricity/annual/html/epa_01_01.html) a. Display this information in a bar graph. b. Which is easier to sketch relatively accurately, a pie chart or a bar chart? c. What is the advantage of using a graph to summarize the results instead of merely stating the percentages for each source? d. What is the modal category?

Step by step solution

01

Understand the Data

The data provides percentages of electricity generated from different sources in 2012 in the U.S. These sources include coal (37%), natural gas (30%), nuclear (19%), hydropower (7%), other renewables such as wind or solar (5%), and other nonrenewable sources (2%).

02

Construct a Bar Graph

To create a bar graph, draw a horizontal or vertical axis. List the different sources of electricity on the x-axis (horizontal axis) and the percentage on the y-axis (vertical axis). For each source, draw a bar up to its percentage. For instance, the bar for coal would reach up to 37%.

03

Compare Bar Graphs and Pie Charts

When deciding between a bar graph and a pie chart, consider accuracy. Bar graphs can be more precise because they use a scale to show the exact percentages, whereas a pie chart relies on visual estimation of angles, which can be less precise.

04

Advantages of Graphical Summaries

Graphs provide a visual representation of data, making it easier to compare categories at a glance and identify trends or patterns, such as which sources are most or least common.

05

Identify the Modal Category

The modal category is the category with the highest percentage. In this case, coal is the modal category since it accounts for 37% of the electricity generation, making it the most frequent among the categories listed.

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Key Concepts

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

Electricity Generation

Electricity generation is the process of converting different forms of energy into electricity that can be used in homes, schools, businesses, and industries. In the United States in 2012, electricity was primarily generated from three main sources: coal, natural gas, and nuclear power plants. Coal was the largest contributor, accounting for 37% of the electricity. This was followed by natural gas at 30% and nuclear energy at 19%. Other notable sources included hydropower at 7%, renewable energy such as wind and solar at 5%, and nonrenewable sources like petroleum at 2%. Understanding where electricity comes from is crucial for several reasons:

• Environmental Impact: Different sources have varying impacts on the environment. For example, coal is known to release more greenhouse gases compared to wind or solar energy.
• Resource Management: Recognizing the sources allows better management and decision-making regarding energy policies and investments.
• Innovation and Development: By analyzing the sources of electricity generation, efforts can be directed towards developing technologies that make energy production cleaner and more efficient.

Data Visualization

Data visualization involves representing data or information in a visual context, such as a chart or graph. It makes complex data more accessible, understandable, and usable. In the context of electricity generation, visualizing the data helps convey the relative contributions of different electricity sources clearly and effectively. When it comes to visualizing this kind of data, bar graphs are particularly useful. Here's why:

• Clarity: Bar graphs display data visually through rectangular bars, making comparisons across categories straightforward. Each bar represents a percentage, making it simple to see which source contributes more or less.
• Precision: Bar graphs use a scale, allowing for more precise reading of data points compared to a pie chart, which relies on angle estimation.
• Ease of Use: Creating a bar graph is generally easy and requires only simple tools—drawing a horizontal or vertical axis and plotting the data can effectively represent the distribution.

Modal Category

The modal category in statistics refers to the category that occurs most frequently in a data set. It's a straightforward concept but very useful in data analysis as it identifies the most common or popular item in a distribution. In the context of electricity generation data from 2012, the modal category is coal. Since coal accounts for 37% of electricity production, it clearly stands out as the category with the highest percentage. Identifying the modal category helps in:

• Quick Understanding: By knowing the modal category, one can instantly identify the leading contributor to electricity generation without going through all the data.
• Targeting Areas for Improvement: Understanding that coal is the modal category can guide discussions about reducing emissions and shifting towards cleaner energy sources.
• Decision Making: Policymakers and companies can use this information to allocate resources, funding, and focus efforts on transitioning to more sustainable options.