Questing on Statistical Hypothesis.....Help Please!?

In a simple random sample of 1000 adult Americans only 430 could name at least one justice on the US Supreme Court. Carry out a hypothesis test to determine if there is convincing evidence to support the claim that fewer than fifty percent of American adults can name at least one sitting justice on the Supreme Court. I think n=1000 Xbar=430 Mu=500 but i'm not sure what test because i don't have a Standard deviation.