A safety officer wants to prove that the average speed of cars driven by a school...

A safety officer wants to prove that the average speed of cars driven by a school is less than 25 mph. Suppose that a random sample of 14 cars shows an average speed of 24.0 mph, with a sample standard deviation of 2.2 mph. Assume that the speeds of cars are normally distributed.

Provide the notation for the underlined value. That is, what does the underlined value represent?

Solutions

Expert Solution

Solution :

Given that,

mean = = 25

standard deviation = = 2.2

n = 14

= 25

= / $\sqrt$ n =2.2 $\sqrt$ 14 = 0.5880

P( < 24 )

P ( - / ) < ( 24 - 25 / 0.5880 )

P ( z < -1 / 0.5880 )

P ( z < -1.70 )

= 0.0446

Probability = 0.0446

orchestra answered 1 year ago

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