Setting Up Null and Alternative Hypotheses
In hypothesis testing, you might need to set up a pair of hypotheses: the current claim (null hypothesis) and the one challenging it (alternative hypothesis). Determine null and alternative hypotheses in the following problems.
Sample questions

You decide to test the published claim that 75% of voters in your town favor a particular school bond issue. What will your null hypothesis be?
Answer: H_{0}: p = 0.75
The null hypothesis is the prior claim that you want to test — in this case, that “75% of voters conclude the bond issue.” The null and alternative hypotheses are always stated in terms of a population parameter (p in this case).

You decide to test the published claim that 75% of voters in your town favor a particular school bond issue. What will your alternative hypothesis be?
Answer:
The alternative hypothesis is the statement about the world that you will conclude if you have statistical evidence to reject the null hypothesis, based on the data. The null and alternative hypotheses are always stated in terms of a population parameter (in this case p).

A university claims that workstudy students earn an average of $10.50 per hour. What is the null hypothesis for a hypothesis test of this statement?
Answer:
The null hypothesis is the original claim or current “best guess” at the value of interest. The null hypothesis is always written in terms of a population parameter being equivalent to a specific value.
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