Math Problem Statement

The highway mileage (mpg) for a sample of 8 different models of a car company can be found below. Find the mean, median, mode, and standard deviation. Round to one decimal place as needed.

20, 23, 26, 27, 29, 31, 35, 35

Mean =

Median =

Mode =

Standard Deviation =

Solution

Let's calculate the required statistics for the given data:

Data:

20, 23, 26, 27, 29, 31, 35, 35

1. Mean:

The mean is the sum of the values divided by the number of values.

Mean=20+23+26+27+29+31+35+358\text{Mean} = \frac{20 + 23 + 26 + 27 + 29 + 31 + 35 + 35}{8}

Mean=2068=25.8\text{Mean} = \frac{206}{8} = 25.8

2. Median:

To find the median, the data must be ordered. The ordered data is already given:

20, 23, 26, 27, 29, 31, 35, 35

Since there are 8 numbers (an even number), the median is the average of the two middle numbers (the 4th and 5th values).

Median=27+292=562=28.0\text{Median} = \frac{27 + 29}{2} = \frac{56}{2} = 28.0

3. Mode:

The mode is the number that appears most frequently. Here, the number 35 appears twice, while all other numbers appear once.

Mode=35\text{Mode} = 35

4. Standard Deviation:

The standard deviation is a measure of the spread of the numbers. We calculate it using the formula:

Standard Deviation=(xiμ)2n\text{Standard Deviation} = \sqrt{\frac{\sum (x_i - \mu)^2}{n}}

Where xix_i represents each data point, μ\mu is the mean, and nn is the number of data points.

  1. Subtract the mean from each data point and square the result:

(2025.8)2=(5.8)2=33.64(20 - 25.8)^2 = (-5.8)^2 = 33.64 (2325.8)2=(2.8)2=7.84(23 - 25.8)^2 = (-2.8)^2 = 7.84 (2625.8)2=(0.2)2=0.04(26 - 25.8)^2 = (0.2)^2 = 0.04 (2725.8)2=(1.2)2=1.44(27 - 25.8)^2 = (1.2)^2 = 1.44 (2925.8)2=(3.2)2=10.24(29 - 25.8)^2 = (3.2)^2 = 10.24 (3125.8)2=(5.2)2=27.04(31 - 25.8)^2 = (5.2)^2 = 27.04 (3525.8)2=(9.2)2=84.64(35 - 25.8)^2 = (9.2)^2 = 84.64 (3525.8)2=(9.2)2=84.64(35 - 25.8)^2 = (9.2)^2 = 84.64

  1. Sum the squared differences:

33.64+7.84+0.04+1.44+10.24+27.04+84.64+84.64=249.5233.64 + 7.84 + 0.04 + 1.44 + 10.24 + 27.04 + 84.64 + 84.64 = 249.52

  1. Divide by the number of data points n=8n = 8:

249.528=31.19\frac{249.52}{8} = 31.19

  1. Take the square root of the result:

Standard Deviation=31.195.6\text{Standard Deviation} = \sqrt{31.19} \approx 5.6


Final Results:

  • Mean = 25.8
  • Median = 28.0
  • Mode = 35
  • Standard Deviation ≈ 5.6

Would you like more details on any of the calculations or another question? Here's a tip for you:

Tip:

When calculating standard deviation, always ensure you're using the correct formula. For a sample, you divide by the number of data points nn, but for a population, you would divide by n1n-1. This is known as "Bessel's correction."

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Math Problem Analysis

Mathematical Concepts

Statistics
Mean
Median
Mode
Standard Deviation

Formulas

Mean = (Sum of values) / n
Median = Average of two middle values (for even number of values)
Mode = Most frequent value
Standard Deviation = sqrt(sum((xi - μ)^2) / n)

Theorems

Bessel's correction for sample standard deviation

Suitable Grade Level

Grades 9-12