Math Problem Statement

Example 5

Consider the two data sets of readings in one of your laboratory activities, Which of the following sets has a larger standard deviation?

Set A. 9 g. 11 g. 5 g. 7 g and 13 g

Set B 11 g. 10 g 19 g. 19 g, and 11 g

Solution

To determine which set has a larger standard deviation, we need to calculate the standard deviation for both Set A and Set B. Standard deviation is a measure of the amount of variation or dispersion in a set of values.

Steps to Calculate Standard Deviation:

  1. Find the mean (average) of each set.
  2. Calculate the squared differences from the mean for each data point.
  3. Find the mean of these squared differences (this is called the variance).
  4. Take the square root of the variance to obtain the standard deviation.

Let's compute these step by step.

Set A: 9 g, 11 g, 5 g, 7 g, 13 g

  1. Mean of Set A: Mean=9+11+5+7+135=455=9g\text{Mean} = \frac{9 + 11 + 5 + 7 + 13}{5} = \frac{45}{5} = 9 \, \text{g}

  2. Squared differences from the mean: (99)2=02=0(9-9)^2 = 0^2 = 0 (119)2=22=4(11-9)^2 = 2^2 = 4 (59)2=(4)2=16(5-9)^2 = (-4)^2 = 16 (79)2=(2)2=4(7-9)^2 = (-2)^2 = 4 (139)2=42=16(13-9)^2 = 4^2 = 16

  3. Variance of Set A: Variance=0+4+16+4+165=405=8\text{Variance} = \frac{0 + 4 + 16 + 4 + 16}{5} = \frac{40}{5} = 8

  4. Standard Deviation of Set A: Standard Deviation=82.83g\text{Standard Deviation} = \sqrt{8} \approx 2.83 \, \text{g}

Set B: 11 g, 10 g, 19 g, 19 g, 11 g

  1. Mean of Set B: Mean=11+10+19+19+115=705=14g\text{Mean} = \frac{11 + 10 + 19 + 19 + 11}{5} = \frac{70}{5} = 14 \, \text{g}

  2. Squared differences from the mean: (1114)2=(3)2=9(11-14)^2 = (-3)^2 = 9 (1014)2=(4)2=16(10-14)^2 = (-4)^2 = 16 (1914)2=52=25(19-14)^2 = 5^2 = 25 (1914)2=52=25(19-14)^2 = 5^2 = 25 (1114)2=(3)2=9(11-14)^2 = (-3)^2 = 9

  3. Variance of Set B: Variance=9+16+25+25+95=845=16.8\text{Variance} = \frac{9 + 16 + 25 + 25 + 9}{5} = \frac{84}{5} = 16.8

  4. Standard Deviation of Set B: Standard Deviation=16.84.10g\text{Standard Deviation} = \sqrt{16.8} \approx 4.10 \, \text{g}

Conclusion:

Set B has a larger standard deviation (approximately 4.10 g) compared to Set A (approximately 2.83 g). This indicates that the values in Set B are more spread out from the mean than the values in Set A.

Would you like more details or have any questions?

Related Questions:

  1. How is variance related to standard deviation?
  2. What does a higher standard deviation imply about a data set?
  3. How can the standard deviation be used in statistical analysis?
  4. What are some real-world applications of standard deviation?
  5. How would the standard deviation change if all values in a set are increased by a constant?
  6. How do outliers affect the standard deviation?
  7. What is the difference between sample standard deviation and population standard deviation?
  8. Why is the square root used in calculating standard deviation?

Tip: When comparing the variability of two data sets, the set with the larger standard deviation is more dispersed around the mean.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Statistics
Standard Deviation
Variance

Formulas

Standard Deviation formula
Variance formula

Theorems

-

Suitable Grade Level

Grades 10-12