SOLUTION: The R. R. Bowker Company collects information on the retail prices of books and publishes its findings in The Bowker Annual Library and Book Trade Almanac. In 2005, the mean retail

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Question 860939: The R. R. Bowker Company collects information on the retail prices of books and publishes its findings in The Bowker Annual Library and Book Trade Almanac. In 2005, the mean retail price of all history books was $78.01. If a sample of size 21 was taken randomly, what is the probability that the mean age of the sample is at least $82? Assume that the standard deviation of this year’s retail prices of all history books is $7.61. State any assumptions that you are making in solving this problem
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

s(sample SD) = 7.61/sqrt(21) = 4.5826

 z = (82-78.01)/s = 3.99/4.5826 = .8707

P(z < .8707) = .8080

P(x ≥ 82) = 1-.8080 = .1919  0r 19.2%