If the p-value is small we reject the null hypothesis. This is to try to stay ahead of the lab. Let's talk a minute about the distribution of the test statistic. That was binomial. Recall that when every possibility was added together the sum was 1.
Integration is just like adding.
The shape of the chi-squared distribution is affected by the degrees of freedom. The lower the degrees of freedom the more skewed the distribution. If you do your calculation and you end up with a negative number you have made a mistake. Table 4.4 Gives the area to the right of a specific cut off point for a given number of degrees of freedom. Write down your decision and the conclusion in words.