Answer:
The degrees of freedom are given by:
![df = n-1=14-1=13](https://img.qammunity.org/2021/formulas/mathematics/college/4s23wj0am40ikf4do1v2nnsbr3ju0jhj4n.png)
The significance level is
and then the critical value can be founded in th chi square table we need a quantile that accumulates 0.05 of the area in the right tail of the distribution and for this case is:
![\chi^2_(\alpha)= 22.362](https://img.qammunity.org/2021/formulas/mathematics/college/qw41avq6l8udxmgk527v7oy3jt77ulk3n9.png)
And if the chi square statistic is higher than the critical value we can reject the null hypothesis in favor of the alternative.
Explanation:
We have the followign system of hypothesis:
Null hypothesis:
![\sigma^2 \leq 3.5](https://img.qammunity.org/2021/formulas/mathematics/college/rezpmamkz21r5on0yem2g0ota6sf3iaw0f.png)
Alternative hypothesis:
![\sigma^2 >3.5](https://img.qammunity.org/2021/formulas/mathematics/college/y0gxo3bza5u6ggbzr4dxtw5ojduymj4te4.png)
The degrees of freedom are given by:
![df = n-1=14-1=13](https://img.qammunity.org/2021/formulas/mathematics/college/4s23wj0am40ikf4do1v2nnsbr3ju0jhj4n.png)
The significance level is
and then the critical value can be founded in th chi square table we need a quantile that accumulates 0.05 of the area in the right tail of the distribution and for this case is:
![\chi^2_(\alpha)= 22.362](https://img.qammunity.org/2021/formulas/mathematics/college/qw41avq6l8udxmgk527v7oy3jt77ulk3n9.png)
And if the chi square statistic is higher than the critical value we can reject the null hypothesis in favor of the alternative.