Math Problem Statement

Please solve

Please solve

Solution

Let's solve the problem step by step.

Part (a) What is the level of significance?

The level of significance is α=0.05\alpha = 0.05 (5%).

Null and Alternative Hypotheses:
  • H0:σ2=47.1H_0: \sigma^2 = 47.1 (The variance is equal to 47.1.)
  • H1:σ2>47.1H_1: \sigma^2 > 47.1 (The variance is greater than 47.1.)

This is a one-tailed chi-square test for variance.


Part (b) Chi-Square Test Statistic

The formula for the chi-square test statistic is:

χ2=(n1)s2σ2\chi^2 = \frac{(n-1) \cdot s^2}{\sigma^2}

Where:

  • n=17n = 17 (sample size),
  • s2=80.5s^2 = 80.5 (sample variance),
  • σ2=47.1\sigma^2 = 47.1 (population variance).

Substitute the values:

χ2=(171)80.547.1=1680.547.127.36\chi^2 = \frac{(17 - 1) \cdot 80.5}{47.1} = \frac{16 \cdot 80.5}{47.1} \approx 27.36

Degrees of Freedom (df): df=n1=16\text{df} = n - 1 = 16

Assumption: We assume the population follows a normal distribution.


Part (c) P-Value of the Sample Test Statistic

Using the chi-square table or software, we determine the p-value for χ2=27.36\chi^2 = 27.36 with df=16df = 16 in a one-tailed test.

  • From tables or software: 0.010<p<0.0250.010 < p < 0.025.

Part (d) Decision: Reject or Fail to Reject H0H_0?

  • The decision rule is: Reject H0H_0 if pαp \leq \alpha.
  • Since p<0.05p < 0.05, we reject the null hypothesis.

Part (e) Interpretation

At the 5% level of significance, there is sufficient evidence to conclude that the variance of annual salaries is greater in Kansas.


Final Answers:

(a) Level of Significance: α=0.05\alpha = 0.05.
H0:σ2=47.1H_0: \sigma^2 = 47.1, H1:σ2>47.1H_1: \sigma^2 > 47.1.

(b) Chi-Square Test Statistic: χ2=27.36\chi^2 = 27.36, df=16df = 16.
Assumption: Normal population distribution.

(c) P-Value: 0.010<p<0.0250.010 < p < 0.025.

(d) Decision: Reject H0H_0.

(e) Interpretation: There is sufficient evidence to conclude the variance is greater in Kansas.


Would you like a detailed breakdown of any step? Here are 5 questions to expand:

  1. How is the chi-square formula derived for variance testing?
  2. Can you explain how to use the chi-square distribution table?
  3. Why is it necessary to assume a normal population distribution?
  4. What happens if α\alpha is changed to a more strict value, e.g., 1%?
  5. What are other statistical tests for variance aside from chi-square?

Tip: Always double-check your dfdf and p-values with tables/software for precision!

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Math Problem Analysis

Mathematical Concepts

Chi-Square Test
Hypothesis Testing
Variance
Statistical Inference

Formulas

\chi^2 = \frac{(n-1) \cdot s^2}{\sigma^2}
df = n - 1

Theorems

Chi-Square Distribution
Hypothesis Testing for Variance

Suitable Grade Level

College/University