The sugar content of the syrup in canned peaches is normally distributed. Suppose that the variance is thought to be $18 \text{mg}^2$. A random sample $n = 10$ of cans yields a sample standard deviation of $s = 4.8$ mg.
Test the hypothesis $H_0: \sigma^2 = 18$ versus $H_a: \sigma^2 \neq 18$ using $\alpha = 0.05$.
Find $p$-value for the test.
The solution is shown below:
I have no idea, now they did $p$-value calculations. Can someone please tell the steps to evaluate $p$-value?