I get this question a lot in my BUS 233 Business Statistics course. It comes when students see a problem similar to the following in their homework or on a quiz:

In a sample of 1000 home buyers, you find that 457 home buyers found their real estate agent through a friend. At α=0.08, can you reject the claim that 50% of home buyers find their real estate agent through a friend?
a) Write the claim mathematically and identify H0 and Ha. (b) Find the critical value(s) and identify the rejection region(s). (c) Find the standardized test statistic. (d) Decide whether to reject or fail to reject the null hypothesis.

If you run into a problem which asks you to find the standardized test statistic but does not give you the standard deviation, it is probably a proportion problem and this one is just that.

Solution:

Ho: p = 0.50; Ha: p ≠ 0.50.