A survey of 100 CEOs finds that 60 think the economy will improve next year. Is there

Question:

A survey of 100 CEOs finds that 60 think the economy will improve next year. Is there evidence that the rate is higher among all CEOs than the 55% reported by the public at large?
a) Find the standard deviation of the sample proportion based on the null hypothesis.
b) Find the z-statistic.
c) Does the z-statistic seem like a particularly large or small value?