A sample of 51 elements is selected to estimate a 95% confidence interval for the variance of the population. The chi-square values to be used for this interval estimation are

a. -1.96 and 1.96
b. 32.357 and 71.420
c, 34.764 and 67.505
d. 12.8786 and 46.9630

Respuesta :

Answer:

Correct option: (b) 32.357 and 71.420

Explanation:

The confidence interval for population variance σ² is:

[tex]\frac{(n-1)s^{2}}{\chi^{2}_{\alpha/2, (n-1) }}\leq \sigma^{2}\leq \frac{(n-1)s^{2}}{\chi^{2}_{(1-\alpha/2), (n-1) }}[/tex]

Given:

[tex]n=51\\\alpha =1-0.95=0.05[/tex]

Compute the critical values of chi-square as follows:

[tex]\chi^{2}_{\alpha/2, (n-1)}=\chi^{2}_{0.025,50}=71.42[/tex]

[tex]\chi^{2}_{(1-\alpha/2), (n-1)}=\chi^{2}_{0.975,50}=32.36[/tex]

Use the chi-square table for the critical value.

Thus, the critical values are 32.36 and 71.42.

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