You want to estimate the percentage of adults who believe that passwords should be replaced with biometric security (such as fingerprints). How many randomly selected adults must you survey? Assume that you want to be 90% confident that the sample percentage is within 2.8 percentage points of the true population percentage.

a. Assume that nothing is known about the percentage of adults who believe that passwords should be replaced with biometric security.
The sample size needed is

b. Assume that a prior survey suggests that about 45% of adults believe that biometric security should replace passwords The sample size needed is ?
c. Does the additional survey information from part (b) have much of an effect on the sample size that is required?
The additional survey information form part (b) causes the required sample size to change by ? 10%. Based on this, the additional survey information causes ? in the sample size that is required