SOLUTION: Speed limit is 65 mph. The mean speed of automobiles was measured at 63 mph with a standard deviation of 8 mph. If the speeds are normally distributed, what percentage of the autom

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Question 405522: Speed limit is 65 mph. The mean speed of automobiles was measured at 63 mph with a standard deviation of 8 mph. If the speeds are normally distributed, what percentage of the automobiles are exceeding the speed lilmit? If the Highway Patrol decides to ticket ony motorist exceeding 72 mph, what percentage of the motorist might they arrest?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi, 

*Note: z+=+blue%28x+-+mu%29%2Fblue%28sigma%29

  z = 65-63/8 = 2/8 = .25

 P(z > .25) = 1-.5987 = .4013

   40.13% are exceeding the speed limit



 z = 72-63/8 = 9/8 = 1.125

P(z> 1.125) = 1 - .8697 = .1303  

13.03% might expect to be exceeding a speed limit of 72mph & be ticketed.