What is the percentage of values in the distribution between 7 and 13? %

A First Course in Probability (10th Edition)
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ISBN:9780134753119
Author:Sheldon Ross
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Chapter1: Combinatorial Analysis
Section: Chapter Questions
Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...
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### Understanding Normal Distribution and the 68-95-99.7 Rule

A normal distribution has a mean of 7 and a standard deviation of 2. Use the 68-95-99.7 rule to find the percentage of values in the distribution between 7 and 13.

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**Question:** 

What is the percentage of values in the distribution between 7 and 13?

[ ] %

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#### Explanation:
To answer this question, you need to understand the 68-95-99.7 rule, which is also known as the empirical rule in statistics.

1. **68% Rule:** This states that approximately 68% of the data within a normal distribution lies within one standard deviation of the mean.
  
2. **95% Rule:** This states that approximately 95% of the data lies within two standard deviations of the mean.
  
3. **99.7% Rule:** This states that approximately 99.7% of the data lies within three standard deviations of the mean.

Given:
- Mean (μ) = 7
- Standard Deviation (σ) = 2

For the distribution between 7 and 13:

- 7 is the mean.
- 13 is 3 standard deviations above the mean (7 + 3*2 = 13).

According to the 68-95-99.7 rule:
- 50% of the data is below the mean (since the normal distribution is symmetrical).
- 68% of the data lies within one standard deviation from the mean (7 ± 2).

Therefore, the percentage of values between 7 and 13 would include half of the 68% and all values from the mean to 3 standard deviations above the mean.

To calculate this:
- 34% of values lie between 7 and 9 (mean to one standard deviation above mean).
- Values from 9 to 13 are two more standard deviations (86.6% - 34% already includes values from mean to one standard deviation above mean).

Adding these percentages together:
- 34% (mean to one standard deviation) + 47.7% (second and third standard deviation above mean) = 81.7%

Thus, the percentage of values in the distribution between 7 and 13 is approximately **81.7%**.
Transcribed Image Text:### Understanding Normal Distribution and the 68-95-99.7 Rule A normal distribution has a mean of 7 and a standard deviation of 2. Use the 68-95-99.7 rule to find the percentage of values in the distribution between 7 and 13. --- **Question:** What is the percentage of values in the distribution between 7 and 13? [ ] % --- #### Explanation: To answer this question, you need to understand the 68-95-99.7 rule, which is also known as the empirical rule in statistics. 1. **68% Rule:** This states that approximately 68% of the data within a normal distribution lies within one standard deviation of the mean. 2. **95% Rule:** This states that approximately 95% of the data lies within two standard deviations of the mean. 3. **99.7% Rule:** This states that approximately 99.7% of the data lies within three standard deviations of the mean. Given: - Mean (μ) = 7 - Standard Deviation (σ) = 2 For the distribution between 7 and 13: - 7 is the mean. - 13 is 3 standard deviations above the mean (7 + 3*2 = 13). According to the 68-95-99.7 rule: - 50% of the data is below the mean (since the normal distribution is symmetrical). - 68% of the data lies within one standard deviation from the mean (7 ± 2). Therefore, the percentage of values between 7 and 13 would include half of the 68% and all values from the mean to 3 standard deviations above the mean. To calculate this: - 34% of values lie between 7 and 9 (mean to one standard deviation above mean). - Values from 9 to 13 are two more standard deviations (86.6% - 34% already includes values from mean to one standard deviation above mean). Adding these percentages together: - 34% (mean to one standard deviation) + 47.7% (second and third standard deviation above mean) = 81.7% Thus, the percentage of values in the distribution between 7 and 13 is approximately **81.7%**.
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