Could you help explain how you find z = -2.326 from the z table, please? Thank you. Much appreciated!
Could you help explain how you find z = -2.326 from the z table, please? Thank you. Much appreciated!
MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
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Could you help explain how you find z = -2.326 from the z table, please? Thank you. Much appreciated!

Transcribed Image Text:**Statistical Analysis of Assembly Time for Medical Devices**
A statistical analysis of a very large sample of fully-assembled medical devices indicates that the length of the assembly time required is normally distributed with a mean value of 240 seconds and a standard deviation of 40 seconds.
Question: 1% of all assemblies will require less than how many seconds? Round the nearest second (integer answer).
Note: There are no graphs or diagrams associated with this text.
![Sure, here is the transcription of the image:
---
**Step 2**
\[ P(z < z_c) = 0.01 \]
∴ \( z = -2.326 \) (∵ z-table)
\[ z = \frac{X - μ}{σ} \]
\[ -2.326 = \frac{X - 240}{40} \]
∴ \( X = 146.96 \)
\[ x ≈ \boxed{147} \, \text{seconds} \]
---
### Explanation:
In this step, we are working with the z-score formula to find \( X \), given a probability and a specified mean (\( μ \)) and standard deviation (\( σ \)).
- We start with the cumulative probability \( P(z < z_c) = 0.01 \).
- From the z-table, we find the corresponding z-score to be \( z = -2.326 \).
- Using the z-score formula: \[ z = \frac{X - μ}{σ} \]
- Given: \( μ = 240 \) and \( σ = 40 \)
- We substitute the values into the formula: \[ -2.326 = \frac{X - 240}{40} \]
- Solving for \( X \), we get \( X = 146.96 \) which is approximately \( 147 \) seconds.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F4a142951-8855-49ab-9dd3-43aaa09eb349%2F8e90455c-bfd6-46e7-9f67-93a3dd816a0a%2F1aou81c_processed.png&w=3840&q=75)
Transcribed Image Text:Sure, here is the transcription of the image:
---
**Step 2**
\[ P(z < z_c) = 0.01 \]
∴ \( z = -2.326 \) (∵ z-table)
\[ z = \frac{X - μ}{σ} \]
\[ -2.326 = \frac{X - 240}{40} \]
∴ \( X = 146.96 \)
\[ x ≈ \boxed{147} \, \text{seconds} \]
---
### Explanation:
In this step, we are working with the z-score formula to find \( X \), given a probability and a specified mean (\( μ \)) and standard deviation (\( σ \)).
- We start with the cumulative probability \( P(z < z_c) = 0.01 \).
- From the z-table, we find the corresponding z-score to be \( z = -2.326 \).
- Using the z-score formula: \[ z = \frac{X - μ}{σ} \]
- Given: \( μ = 240 \) and \( σ = 40 \)
- We substitute the values into the formula: \[ -2.326 = \frac{X - 240}{40} \]
- Solving for \( X \), we get \( X = 146.96 \) which is approximately \( 147 \) seconds.
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