SOLUTION: A statistical analysis of 1,000 long-distance telephone calls made by a company indicates that the length of these calls is normally distributed, with a mean of 270 seconds and a

SOLUTION: A statistical analysis of 1,000 long-distance telephone calls made by a company indicates that the length of these calls is normally distributed, with a mean of 270 seconds and a

Algebra.Com

Question 1189194: A statistical analysis of 1,000 long-distance telephone calls made by a company indicates that the length of these calls is normally distributed, with a mean of 270 seconds and a standard deviation of 30 seconds. What is the length of a call if only 1% of all calls are shorter?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
The z-value for 0.01 is -2.326
z=(x-mean)/sd=(x-270)/30
-69.8=x-270
x=200.2 minutes
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