SOLUTION: 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

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Question 1155775: 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 95​% 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.
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
the error is +/-1.96*sqrt(p*(1-p)/n)=0.08
assume p=0.5. This will give the most conservative estimate
square both sides
3.84(0.5*0.5/n)=0.0064
0.91/n=0.0064
n=0.91/0.0064=142.18 or rounding up to 143 people.