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Assume the speed of vehicles along a stretch of i-10 has an approximately normal distribution with a mean of 71 mph and a standard deviation of 8 mph. the current speed limit is 65 mph. what is the proportion of vehicles less than or equal to the speed limit?

Respuesta :

altavistard
Find  z = (value - mean) / (std dev), which here is
         65 - 71
z = -------------- = -6/8 = -3/4 = -0.75.

Using a table of z-scores, find the area to the left of z = -0.75.
             8

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