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In automobile mileage and gasoline-consumption testing, 13 automobiles were road tested for 300 miles in both city and highway driving conditions. The following data were recorded for miles-per-gallon performance. \\[\text { City: } \quad 16.2 \quad 16.7 \quad 15.9 \quad 14.4 \quad 13.2 \quad 15.3 \quad 16.8 \quad 16.0 \quad 16.1 \quad 15.3 \quad 15.2 \quad 15.3 \quad 16.2\\] Highway: \(19.4 \quad 20.6 \quad 18.3 \quad 18.6 \quad 19.2 \quad 17.4 \quad 17.2 \quad 18.6 \quad 19.021 .1 \quad 19.4 \quad 18.5 \quad 18.7\) Use the mean, median, and mode to make a statement about the difference in performance for city and highway driving.

Short Answer

Expert verified
Highway driving shows better mileage than city driving based on mean, median, and mode.

Step by step solution

01

Calculate the Mean for City Driving

The mean is the average of all data points. Add up all the city MPG values and divide by the number of values, which is 13. \[\text{Mean}_{\text{City}} = \frac{16.2 + 16.7 + 15.9 + 14.4 + 13.2 + 15.3 + 16.8 + 16.0 + 16.1 + 15.3 + 15.2 + 15.3 + 16.2}{13} = \frac{192.4}{13} \approx 14.8\]
02

Calculate the Mean for Highway Driving

Add up all the highway MPG values and divide by the number of values, which is 13.\[\text{Mean}_{\text{Highway}} = \frac{19.4 + 20.6 + 18.3 + 18.6 + 19.2 + 17.4 + 17.2 + 18.6 + 19.0 + 21.1 + 19.4 + 18.5 + 18.7}{13} = \frac{245.0}{13} \approx 18.8\]
03

Determine the Median for City Driving

The median is the middle value when the data points are ordered. Arrange the city MPG values in ascending order and find the middle one.Ordered data: \[13.2, 14.4, 15.2, 15.3, 15.3, 15.3, 15.9, 16.0, 16.1, 16.2, 16.2, 16.7, 16.8\]With 13 values, the median is the 7th value: 15.9.
04

Determine the Median for Highway Driving

Order the highway MPG values and find the middle one.Ordered data: \[17.2, 17.4, 18.3, 18.5, 18.6, 18.6, 18.7, 19.0, 19.2, 19.4, 19.4, 20.6, 21.1\]With 13 values, the median is the 7th value: 18.7.
05

Identify the Mode for City Driving

The mode is the most frequently occurring value. In the city data, 15.3 appears three times, more often than any other value.
06

Identify the Mode for Highway Driving

Check the frequency of each value. In the highway data, 18.6 and 19.4 each appear twice, making both the modes. This dataset is bimodal.
07

Interpret the Results

The mean and median suggest that highway mileage is better than city mileage (mean: 14.8 city vs 18.8 highway, median: 15.9 city vs 18.7 highway). The mode supports this as well (city mode: 15.3, highway modes: 18.6 and 19.4), indicating that typical highway performance is superior.

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Key Concepts

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

Mean Calculation
The mean, often referred to as the average, is a fundamental concept in descriptive statistics used to summarize a set of numbers.
To calculate the mean, you need to add up all the figures and then divide by the number of values in the data set. This step gives you a single value that represents the data set.
For instance, in the exercise on automobile mileage, we calculate the mean for both city and highway driving to compare the performances.
  • City Driving Mean: The sum of all city miles-per-gallon (MPG) data points is 192.4. Dividing this by 13 cars gives a mean of approximately 14.8 MPG.
  • Highway Driving Mean: By summing highway MPG data points, we get 245.0, and dividing by 13 gives a mean of approximately 18.8 MPG.
Understanding the mean helps in detecting the overall trend. Here, it shows that generally, cars perform better in highway conditions than in city driving.
Median Calculation
The median is a measure that indicates the middle value of a dataset, providing a central tendency indicator.
This concept is especially useful in datasets with outliers, as it is not skewed by extremely high or low values.
To find the median, arrange the data points in ascending order, then locate the middle value. In a dataset with an odd number of values, the median is straightforward.
  • City Median: Once the city MPG data is ordered, the median is the 7th value, which is 15.9 MPG.
  • Highway Median: With the highway MPG data in order, the median falls at 18.7 MPG, which is the 7th value in this dataset.
The median confirms findings from the mean calculation, highlighting that typical performance is better on highways.
Mode Identification
The mode represents the value that appears most frequently in a dataset. It is an essential measure of central tendency.
Sometimes, a dataset can have no mode, one mode, or multiple modes, known as bimodal or multimodal data.
Identifying the mode helps in understanding the most common performance metric among measurements.
  • City Driving Mode: In the city MPG data, 15.3 appears three times, making it the mode.
  • Highway Driving Mode: For highway MPG, the values 18.6 and 19.4 each appear twice, hence the dataset is bimodal.
Having these modes allows us to see which figures are most common and to note that highway MPG data shows multiple typical values, reinforcing better overall performance compared to city driving.

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Most popular questions from this chapter

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