SOLUTION: People were polled on how many books they read the previous year. How many subjects are needed to estimate the number of books read the previous year within one book with 95​

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Question 1121476: People were polled on how many books they read the previous year. How many subjects are needed to estimate the number of books read the previous year within one book with 95​% ​confidence? Initial survey results indicate that sigmaequals19.5 books.
A 95 % confidence level requires
nothing subjects.
​(Round up to the nearest whole number as​ needed.)
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
use z first and then change to t
half interval is z*sigma/sqrt(n)=1.96*19.5/sqrt(n) and that equals 1
multiply by sqrt (n) and then square both sides
3.84^2*19.5^2=1460.77 or 1461 ANSWER
This will be the same for t or z.