SOLUTION: The average age of Amtrak passenger train cars is 19.4 years. If the distribution of ages is normal and 19% of the cars are older than 21.7 years, find the standard deviation.

Question 1081764: The average age of Amtrak passenger train cars is 19.4 years. If the distribution of ages is normal and 19% of the cars are older than 21.7 years, find the standard deviation.
Answer by Fombitz(32388) (Show Source): You can put this solution on YOUR website!
So when , the z score will correlate to an age of 21.7.
For ,

Work that out for the answer.

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