Two friends have decided to take a Welding class together. Virgil got 38 on the first quiz of the semester. The class average on the first quiz was 42 with a standard deviation of 5. Mohammad, who was absent when the first quiz was given, got 40 on the second quiz. The class average on the second quiz was 45 with a standard deviation of 6.1. Virgil was absent for the second quiz. After the second quiz, Mohammad told Virgil that he was doing better in class because they had each taken one quiz, and he had earned the higher score. Did Mohammad really perform better than Virgil?

MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
icon
Related questions
Question
**Case Study: Comparing Performance Using Z-Scores**

Two friends, Virgil and Mohammad, have decided to take a welding class together. Here's a breakdown of their performance on quizzes:

- **Virgil's Score Summary:**
  - First Quiz: Virgil scored 38.
  - Class average: 42
  - Standard deviation: 5

- **Mohammad's Score Summary:**
  - Second Quiz: Mohammad scored 40.
  - Class average: 45
  - Standard deviation: 6.1

### Analysis:

**Objective:** Determine if Mohammad really performed better than Virgil based on their quiz scores using z-scores for comparison.

**Definitions:**

- **Z-Score Formula:** 

  \[
  Z = \frac{(X - \text{Mean})}{\text{Standard Deviation}}
  \]

- **Calculation:**

  - **Virgil’s Z-Score:**
    \[
    Z_{\text{Virgil}} = \frac{38 - 42}{5} = \frac{-4}{5} = -0.8
    \]

  - **Mohammad’s Z-Score:**
    \[
    Z_{\text{Mohammad}} = \frac{40 - 45}{6.1} = \frac{-5}{6.1} \approx -0.82
    \]

### Conclusion:

Based on the z-scores:

- **Z-Mohammad ≈ -0.82** is slightly more negative than **Z-Virgil = -0.8.**

Therefore, Mohammad did not perform better than Virgil when comparing their performances relative to their respective class averages and standard deviations.

#### Options to Consider:

- **Yes. \(Z_{\text{Mohammad}}\) is more negative than \(Z_{\text{Virgil}}\).**

- **Yes. \(Z_{\text{Mohammad}}\) is less negative than \(Z_{\text{Virgil}}\).**

- **No. \(Z_{\text{Mohammad}}\) is less negative than \(Z_{\text{Virgil}}\).**

- **No. \(Z_{\text{Mohammad}}\) is more negative than \(Z_{\text{Virgil}}\).**

**Correct Evaluation:**
- The correct choice is:
  - **No. \(Z_{\text{Mohammad}}\) is more negative than \(Z_{\text{Virgil
Transcribed Image Text:**Case Study: Comparing Performance Using Z-Scores** Two friends, Virgil and Mohammad, have decided to take a welding class together. Here's a breakdown of their performance on quizzes: - **Virgil's Score Summary:** - First Quiz: Virgil scored 38. - Class average: 42 - Standard deviation: 5 - **Mohammad's Score Summary:** - Second Quiz: Mohammad scored 40. - Class average: 45 - Standard deviation: 6.1 ### Analysis: **Objective:** Determine if Mohammad really performed better than Virgil based on their quiz scores using z-scores for comparison. **Definitions:** - **Z-Score Formula:** \[ Z = \frac{(X - \text{Mean})}{\text{Standard Deviation}} \] - **Calculation:** - **Virgil’s Z-Score:** \[ Z_{\text{Virgil}} = \frac{38 - 42}{5} = \frac{-4}{5} = -0.8 \] - **Mohammad’s Z-Score:** \[ Z_{\text{Mohammad}} = \frac{40 - 45}{6.1} = \frac{-5}{6.1} \approx -0.82 \] ### Conclusion: Based on the z-scores: - **Z-Mohammad ≈ -0.82** is slightly more negative than **Z-Virgil = -0.8.** Therefore, Mohammad did not perform better than Virgil when comparing their performances relative to their respective class averages and standard deviations. #### Options to Consider: - **Yes. \(Z_{\text{Mohammad}}\) is more negative than \(Z_{\text{Virgil}}\).** - **Yes. \(Z_{\text{Mohammad}}\) is less negative than \(Z_{\text{Virgil}}\).** - **No. \(Z_{\text{Mohammad}}\) is less negative than \(Z_{\text{Virgil}}\).** - **No. \(Z_{\text{Mohammad}}\) is more negative than \(Z_{\text{Virgil}}\).** **Correct Evaluation:** - The correct choice is: - **No. \(Z_{\text{Mohammad}}\) is more negative than \(Z_{\text{Virgil
Expert Solution
Step 1

Here,

Two friends have decided to take a welding class together 
Virgil got 38 on the first quiz
The class average on the first quiz was 42, with a standard deviation of 5

Mohammad got 40 on the second  quiz
The class average on the first quiz was 45, with a standard deviation of 6.1

We have to find who did better

 

steps

Step by step

Solved in 2 steps

Blurred answer
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
MATLAB: An Introduction with Applications
MATLAB: An Introduction with Applications
Statistics
ISBN:
9781119256830
Author:
Amos Gilat
Publisher:
John Wiley & Sons Inc
Probability and Statistics for Engineering and th…
Probability and Statistics for Engineering and th…
Statistics
ISBN:
9781305251809
Author:
Jay L. Devore
Publisher:
Cengage Learning
Statistics for The Behavioral Sciences (MindTap C…
Statistics for The Behavioral Sciences (MindTap C…
Statistics
ISBN:
9781305504912
Author:
Frederick J Gravetter, Larry B. Wallnau
Publisher:
Cengage Learning
Elementary Statistics: Picturing the World (7th E…
Elementary Statistics: Picturing the World (7th E…
Statistics
ISBN:
9780134683416
Author:
Ron Larson, Betsy Farber
Publisher:
PEARSON
The Basic Practice of Statistics
The Basic Practice of Statistics
Statistics
ISBN:
9781319042578
Author:
David S. Moore, William I. Notz, Michael A. Fligner
Publisher:
W. H. Freeman
Introduction to the Practice of Statistics
Introduction to the Practice of Statistics
Statistics
ISBN:
9781319013387
Author:
David S. Moore, George P. McCabe, Bruce A. Craig
Publisher:
W. H. Freeman