In a survey, 1388 of 1735 adults surveyed said that they would alter their shopping habits if gas prices remain high. The article did not say how the sample was selected, but for purposes of this exercise, assume that it is reasonable to regard this sample as representative of adult Americans. Based on these survey data, is it reasonable to conclude that more than three-quarters of adult Americans plan to alter their shopping habits if gas prices remain high? (Use α = 0.01. Round your test statistic to two decimal places and your P-value to four decimal places.)
z= ?
What formula do i use?

Question

In a survey, 1388 of 1735 adults surveyed said that they would alter their shopping habits if gas prices remain high. The article did not say how the sample was selected, but for purposes of this exercise, assume that it is reasonable to regard this sample as representative of adult Americans. Based on these survey data, is it reasonable to conclude that more than three-quarters of adult Americans plan to alter their shopping habits if gas prices remain high? (Use α = 0.01. Round your test statistic to two decimal places and your P-value to four decimal places.) 
z= ? 
What formula do i use?