Heights of female students are normally distributed with a mean of 64.2 in and a standard deviation

Question:

Heights of female students are normally distributed with a mean of 64.2 in and a standard deviation of 2.6 in. How many female students must be surveyed if we want to estimate the percentage who are taller than 5 ft? Assume that we want 98%.confidence that the error is no more than 2.5 percentage points.