Suppose a mutual fund qualifies as having moderate risk if the standard deviation of its monthly rate of return is less than 4%. A mutual-fund rating agency randomly selects 21 months and determines the rate of return for a certain fund. The standard deviation of the rate of return is computed to be 2.63%. Is there sufficient evidence to conclude that the fund has moderate risk at the α = 0.05 level of significance? A normal probability plot indicates that the monthly rates of return are normally distributed. Use technology to determine the P-value for the test statistic. The P-value is. (Round to three decimal places as needed.) ... 4

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### Understanding P-Value in Hypothesis Testing

**Problem Statement:**

Suppose a mutual fund qualifies as having moderate risk if the standard deviation of its monthly rate of return is less than 4%. A mutual fund rating agency randomly selects 21 months and determines the rate of return for a certain fund. The standard deviation of the rate of return is computed to be 2.63%. Is there sufficient evidence to conclude that the fund has moderate risk at the α = 0.05 level of significance? A normal probability plot indicates that the monthly rates of return are normally distributed.

**Step-by-Step Solution:**

1. **Null Hypothesis (H0):**
   - The standard deviation of the mutual fund's rate of return is equal to or greater than 4%.
   - \(\sigma \geq 4\%\)

2. **Alternative Hypothesis (H1):**
   - The standard deviation of the mutual fund's rate of return is less than 4%.
   - \(\sigma < 4\%\)

3. **Given Data:**
   - Sample size, \(n = 21\)
   - Sample standard deviation, \(s = 2.63\%\)
   - Population standard deviation threshold, \(\sigma = 4\%\)
   - Significance level, \(\alpha = 0.05\)

4. **Use technology to determine the P-value for the test statistic.**

   You'll need to use a statistical software or calculator to determine the precise P-value. The general process involves using the chi-square distribution because it is based on the sample standard deviation and the sample size. 

5. **P-Value Calculation:**

   The formula for the test statistic using chi-square distribution is:

   \[
   \chi^2 = \frac{(n-1)s^2}{\sigma^2}
   \]

   Substitute the given values:

   \[
   \chi^2 = \frac{(21-1)(2.63)^2}{(4)^2}
   \]

   \[
   \chi^2 = \frac{20 \times 6.9169}{16}
   \]

   \[
   \chi^2 = \frac{138.338}{16}
   \]

   \[
   \chi^2 \approx 8.646
   \]

    Next, use a chi-square distribution table or technology to
Transcribed Image Text:### Understanding P-Value in Hypothesis Testing **Problem Statement:** Suppose a mutual fund qualifies as having moderate risk if the standard deviation of its monthly rate of return is less than 4%. A mutual fund rating agency randomly selects 21 months and determines the rate of return for a certain fund. The standard deviation of the rate of return is computed to be 2.63%. Is there sufficient evidence to conclude that the fund has moderate risk at the α = 0.05 level of significance? A normal probability plot indicates that the monthly rates of return are normally distributed. **Step-by-Step Solution:** 1. **Null Hypothesis (H0):** - The standard deviation of the mutual fund's rate of return is equal to or greater than 4%. - \(\sigma \geq 4\%\) 2. **Alternative Hypothesis (H1):** - The standard deviation of the mutual fund's rate of return is less than 4%. - \(\sigma < 4\%\) 3. **Given Data:** - Sample size, \(n = 21\) - Sample standard deviation, \(s = 2.63\%\) - Population standard deviation threshold, \(\sigma = 4\%\) - Significance level, \(\alpha = 0.05\) 4. **Use technology to determine the P-value for the test statistic.** You'll need to use a statistical software or calculator to determine the precise P-value. The general process involves using the chi-square distribution because it is based on the sample standard deviation and the sample size. 5. **P-Value Calculation:** The formula for the test statistic using chi-square distribution is: \[ \chi^2 = \frac{(n-1)s^2}{\sigma^2} \] Substitute the given values: \[ \chi^2 = \frac{(21-1)(2.63)^2}{(4)^2} \] \[ \chi^2 = \frac{20 \times 6.9169}{16} \] \[ \chi^2 = \frac{138.338}{16} \] \[ \chi^2 \approx 8.646 \] Next, use a chi-square distribution table or technology to
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