The brand manager for a brand of toothpaste must plan a campaign designed to increase brand recognition. He wants to first determine the percentage of adults who have heard of the brand. How many adults must he survey in order to be 80% confident that his estimate is within eight percentage points of the true population percentage? a) Assume that nothing is known about the percentage of adults who have heard of the brand. N= B) Assume that a recent survey suggest that about 79% of adults have heard of the brand. N=