Two identical machines are used to make a special coin. We want to know if they have the same variability. A random sample is taken from each machine :
$$ \begin{matrix} MachineA & 135 & 138 & 136 & 140 & 138 & 135 & 139 \\ MachineB & 140 & 135 & 140 & 138 & 135 & 138 & 140 \\ \end{matrix} $$
I have to give the test to use and do it with $\alpha=0.05$
Edit:
I ended up using F-test. First machine variance is $3.9$ Second machine variance is $5$
$F = 5 / 3.9$
Critical value for df 6,6 with $\alpha = 0.05$ is $4.28$
Since the p-value is greater than $\alpha$ then the observed outcome was likely enough that it is reasonable to assume that the null hypothesis is true so fail to reject the null hypothesis.