SOLUTION: The speed limit in the state of Ohio is 55 miles per hour. On a certain stretch of interstate highway the mean speed of traffic (as checked by radar) is 58 miles per hour with a s

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Question 453028: The speed limit in the state of Ohio is 55 miles per hour. On a certain stretch of interstate highway the mean speed of traffic (as checked by radar) is 58 miles per hour with a standard deviation of 4 miles per hour. The speeds of vehicles on this section of highway are normally distributed.
What percentage of vehicles are exceeding the speed limit?
Above what speed are the top 5% of the speeders travelling?

Thanks so much for your help!

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The speed limit in the state of Ohio is 55 miles per hour. On a certain stretch of interstate highway the mean speed of traffic (as checked by radar) is 58 miles per hour with a standard deviation of 4 miles per hour. The speeds of vehicles on this section of highway are normally distributed.
What percentage of vehicles are exceeding the speed limit?
Above what speed are the top 5% of the speeders travelling?
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Find the z-value with a right tail of 5%:
z = 1.645
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Find the corresponding speed value:
x = zs+u
x = 1.645*4+58
x = 64.58 mph
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Cheers,
Stan H.