From generation to generation, the mean age when smokers first start to smoke varies. However, the standard deviation of that age remains constant at around 2.1 years. A survey of 42 smokers of this generation was done to see if the mean starting age is at least 19. The sample mean was 18.2 with a sample standard deviation of 1.3. Do the data support the claim at the 5% level?

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

From generation to generation, the mean age when smokers first start to smoke varies. However, the standard deviation of that age remains constant at around 2.1 years. A survey of 42 smokers of this generation was done to see if the mean starting age is at least 19. The sample mean was 18.2 with a sample standard deviation of 1.3. Do the data support the claim at the 5% level?

Note: If you are using a Student's t-distribution for the problem, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.)

I need help solving the problems in the pictures. 

### Hypothesis Testing and Confidence Intervals

#### Instructions for Hypothesis Testing:

1. **Indicate the correct decision ("reject" or "do not reject" the null hypothesis), the reason for it, and write an appropriate conclusion.**

   - **(i) Alpha (α):** 
     - Enter an exact number as an integer, fraction, or decimal.

   - **(ii) Decision:**
     - ☐ Reject the null hypothesis
     - ☐ Do not reject the null hypothesis

   - **(iii) Reason for Decision:**
     - ☐ Since α < p-value, we reject the null hypothesis.
     - ☐ Since α > p-value, we do not reject the null hypothesis.
     - ☐ Since α < p-value, we do not reject the null hypothesis.
     - ☐ Since α > p-value, we reject the null hypothesis.

   - **(iv) Conclusion:**
     - ☐ There is sufficient evidence to conclude that the starting age for smoking in this generation is less than 19.
     - ☐ There is not sufficient evidence to conclude that the starting age for smoking in this generation is less than 19.

#### Part (i): Confidence Interval Construction

- **Objective:** Construct a 95% confidence interval for the true mean.

- **Steps:**
  - Sketch the graph of the situation.
  - Label the point estimate and the lower and upper bounds of the confidence interval.
  - Round your lower and upper bounds to two decimal places.

- **Graph Explanation:**

  The graph is a normal distribution curve depicting a 95% confidence interval (95% C.I.). The confidence interval is symmetrical around the central mean value:

  - **Point Estimate:** Represents the central value of the interval.
  - **Lower Bound:** 17.6
  - **Upper Bound:** 18.8
  - **Width of Interval:** 1.2

  The curve visually demonstrates the range within which the true mean is expected to fall, with 95% certainty.
Transcribed Image Text:### Hypothesis Testing and Confidence Intervals #### Instructions for Hypothesis Testing: 1. **Indicate the correct decision ("reject" or "do not reject" the null hypothesis), the reason for it, and write an appropriate conclusion.** - **(i) Alpha (α):** - Enter an exact number as an integer, fraction, or decimal. - **(ii) Decision:** - ☐ Reject the null hypothesis - ☐ Do not reject the null hypothesis - **(iii) Reason for Decision:** - ☐ Since α < p-value, we reject the null hypothesis. - ☐ Since α > p-value, we do not reject the null hypothesis. - ☐ Since α < p-value, we do not reject the null hypothesis. - ☐ Since α > p-value, we reject the null hypothesis. - **(iv) Conclusion:** - ☐ There is sufficient evidence to conclude that the starting age for smoking in this generation is less than 19. - ☐ There is not sufficient evidence to conclude that the starting age for smoking in this generation is less than 19. #### Part (i): Confidence Interval Construction - **Objective:** Construct a 95% confidence interval for the true mean. - **Steps:** - Sketch the graph of the situation. - Label the point estimate and the lower and upper bounds of the confidence interval. - Round your lower and upper bounds to two decimal places. - **Graph Explanation:** The graph is a normal distribution curve depicting a 95% confidence interval (95% C.I.). The confidence interval is symmetrical around the central mean value: - **Point Estimate:** Represents the central value of the interval. - **Lower Bound:** 17.6 - **Upper Bound:** 18.8 - **Width of Interval:** 1.2 The curve visually demonstrates the range within which the true mean is expected to fall, with 95% certainty.
### Hypothesis Testing: One Sample

#### Part (d)
State the distribution to use for the test. (Round your answers to four decimal places.)

\[ \bar{X} \sim z \left(\text{______, ______}\right) \]

#### Part (e)
What is the test statistic? (If using the z distribution, round your answers to two decimal places, and if using the t distribution, round your answers to three decimal places.)

\[ z = -2.4096 \]

#### Part (f)
What is the p-value? (Round your answer to four decimal places.)

\[ \text{p-value:} \; \_ \]

**Explain what the p-value means for this problem:**

- ( ) If \( H_0 \) is false, then there is a chance equal to the p-value that the average age of people when they first begin to smoke is not 18.2 years or less.
- ( ) If \( H_0 \) is true, then there is a chance equal to the p-value that the average age of people when they first begin to smoke is not 18.2 years or less.
- ( ) If \( H_0 \) is false, then there is a chance equal to the p-value that the average age of people when they first begin to smoke is 18.2 years or less.
- ( ) If \( H_0 \) is true, then there is a chance equal to the p-value that the average age of people when they first begin to smoke is 18.2 years or less.

#### Part (g)
Sketch a picture of this situation. Label and scale the horizontal axis and shade the region(s) corresponding to the p-value.

**Diagrams:**

1. **First Distribution Diagram:**
   - **Horizontal Axis:** Labeled with \( \mu \) and \(\bar{X}\).
   - **Normal Curve:** Symmetrical.
   - **Shaded Region:** Indicates the p-value on the left side.

2. **Second Distribution Diagram (Highlighted):**
   - **Horizontal Axis:** Labeled with \( \mu \) and \(\bar{X}\).
   - **Normal Curve:** Symmetrical.
   - **Shaded Region:** Indicates the p-value on the right side.

3. **Third Distribution Diagram:**
   - **Horizontal Axis:** Labeled with \( \mu \) and \(\
Transcribed Image Text:### Hypothesis Testing: One Sample #### Part (d) State the distribution to use for the test. (Round your answers to four decimal places.) \[ \bar{X} \sim z \left(\text{______, ______}\right) \] #### Part (e) What is the test statistic? (If using the z distribution, round your answers to two decimal places, and if using the t distribution, round your answers to three decimal places.) \[ z = -2.4096 \] #### Part (f) What is the p-value? (Round your answer to four decimal places.) \[ \text{p-value:} \; \_ \] **Explain what the p-value means for this problem:** - ( ) If \( H_0 \) is false, then there is a chance equal to the p-value that the average age of people when they first begin to smoke is not 18.2 years or less. - ( ) If \( H_0 \) is true, then there is a chance equal to the p-value that the average age of people when they first begin to smoke is not 18.2 years or less. - ( ) If \( H_0 \) is false, then there is a chance equal to the p-value that the average age of people when they first begin to smoke is 18.2 years or less. - ( ) If \( H_0 \) is true, then there is a chance equal to the p-value that the average age of people when they first begin to smoke is 18.2 years or less. #### Part (g) Sketch a picture of this situation. Label and scale the horizontal axis and shade the region(s) corresponding to the p-value. **Diagrams:** 1. **First Distribution Diagram:** - **Horizontal Axis:** Labeled with \( \mu \) and \(\bar{X}\). - **Normal Curve:** Symmetrical. - **Shaded Region:** Indicates the p-value on the left side. 2. **Second Distribution Diagram (Highlighted):** - **Horizontal Axis:** Labeled with \( \mu \) and \(\bar{X}\). - **Normal Curve:** Symmetrical. - **Shaded Region:** Indicates the p-value on the right side. 3. **Third Distribution Diagram:** - **Horizontal Axis:** Labeled with \( \mu \) and \(\
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps

Blurred answer
Knowledge Booster
Basics of Inferential Statistics
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, statistics and related others by exploring similar questions and additional content below.
Similar 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