Create a null and a alternative hypothesis, your own example. Now this is one way to state the rule for writing a hypothesis test, "In setting up a hypothesis test, the claim should always be written in the alternative hypothesis." So here is what this means, the null hypothesis is always that the world has not changed. The alternative hypothesis is the challenge, the world is different. Here is the sort of thing I am looking for. For the past seven years, when it rains my newspaper is wet 85% of the time. The newspapers is now delivered by a new person. I am hoping that this means my newspaper will be dry even on rainy days. The null hypothesis is nothing in fact has changes, 85% of the time my paper will be wet on rainy days. The challenger, the alternative hypothesis, my newspaper will not be wet 85% on rainy days, i.e. the world has changed. Now make your own.