Vision Correction A manufacturing company is considering entering the new market of eyeglasses. How many people must be surveyed in order to be 90% confident that the estimated percentage of adults who wear eyeglasses is within three percentage points of the true population percentage?

a. Assume that nothing is known about the percentage of adults who wear eyeglasses.

b. Assume that about 53% of adults wear eyeglasses (based on a Vision Council prior survey).

c. Given that the required sample size is relatively small, could you simply survey the adults that you know?