Evaluate the expression 4(x - 3) + 7 using x=2
2 answers:
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Answer:
Standard deviation = 11.30 m/h
Mean = 57.74 m/h
Step-by-step explanation:
Assume that the travel speed is normally distributed.
The corresponding z-score to the 5th and 90th percentile of normal distribution are, respectively, -1.645 and 1.282.
For any given speed X, the z-score is:
If z = -1.645 for X = 39.15 and z= 1.282 for X=72.23, the following system can be solved for the mean and standard deviation of vehicle speed:
The standard deviation is 11.30 m/h and the mean is 57.74 m/h.