SOLUTION: suppose the average age of a passenger train car is 19.3 years. If the distribution of ages is normal and 10% of the cars are older than 22.2 years, find the standard deviation. p

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Question 752357: suppose the average age of a passenger train car is 19.3 years. If the distribution of ages is normal and 10% of the cars are older than 22.2 years, find the standard deviation. please round your final answer to two decimal places.
Answer by reviewermath(1029) About Me  (Show Source):
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Q: suppose the average age of a passenger train car is 19.3 years. If the distribution of ages is normal and 10% of the cars are older than 22.2 years, find the standard deviation. please round your final answer to two decimal places.
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A:
P(X > 22.2) = 0.10
P%28Z+%3E+%2822.2+-+19.3%29%2Fsigma%29 = 0.10
%2822.2+-+19.3%29%2Fsigma = z%5B0.10%5D = 1.282
sigma = %2822.2+-+19.3%29%2F1.282
standard deviation, sigma = highlight%282.26%29