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State the appropriate null and alternative hypothesis and find the critical value for a left-tailed test with [tex]\alpha=0.10[/tex] and [tex]n=23[/tex]. Use [tex]\sigma^2=169[/tex].

A)
[tex]H_0: \sigma^2 = 169[/tex]
[tex]H_1: \sigma^2 \ \textgreater \ 169[/tex]
C.V. = 14.042
C.V. = 14.848

B)
[tex]H_0: \sigma^2 = 169[/tex]
[tex]H_1: \sigma^2 \ \textless \ 169[/tex]
C.V. = 14.848
C.V. = 14.042


Sagot :

To solve this problem, we need to state the null and alternative hypotheses and find the critical value for a left-tailed test with [tex]\(\alpha = 0.10\)[/tex] and [tex]\(n = 23\)[/tex] using [tex]\(\sigma^2 = 169\)[/tex].

### Step-by-Step Solution:

1. State the Null and Alternative Hypotheses:
- The null hypothesis ([tex]\(H_0\)[/tex]) represents the default or the status quo assumption. In this case, we assume that the true variance [tex]\(\sigma^2\)[/tex] is equal to 169.
[tex]\[ H_0: \sigma^2 = 169 \][/tex]
- The alternative hypothesis ([tex]\(H_1\)[/tex]) represents what we want to test against the null. Since this is a left-tailed test, we are testing if the variance [tex]\(\sigma^2\)[/tex] is less than 169.
[tex]\[ H_1: \sigma^2 < 169 \][/tex]

2. Determine the Degrees of Freedom:
- Degrees of freedom [tex]\(df\)[/tex] for the chi-squared distribution is calculated using the formula:
[tex]\[ df = n - 1 \][/tex]
- Given [tex]\(n = 23\)[/tex]:
[tex]\[ df = 23 - 1 = 22 \][/tex]

3. Find the Critical Value:
- For a left-tailed test, we need the critical value for the chi-squared distribution with [tex]\(22\)[/tex] degrees of freedom and [tex]\(\alpha = 0.10\)[/tex].
- The critical value ([tex]\(C.V.\)[/tex]) for this scenario is obtained from chi-squared distribution tables or by using statistical software to find the point such that the area to the left under the chi-squared curve with 22 degrees of freedom is 0.10.

Based on this information, the appropriate null and alternative hypotheses and the critical value are:

[tex]\[ \boxed{\begin{aligned} & H_0: \sigma^2 = 169 \\ &H_1: \sigma^2 < 169 \\ & \text{Critical Value} = 14.042 \end{aligned}} \][/tex]

Thus, among the given options, the correct choice is:

[tex]\[ D) H_{o:} \sigma^2 = 169, H_{1:} \sigma^2 < 169, \overline{\text{C. V. }} = 14.042 \][/tex]