In the same 2012 survey conducted in Exercise 43, Gallup reported that 66% of American investors say that the federal budget deficit is hurting the U.S. investment climate “a lot.” Is there any evidence that the percentage has decreased from the 79% reported in September 2011?

a) Find the z-score of the observed proportion.

b) Is there evidence that the proportion has decreased?

c) Explain your conclusion.