A racing car consumes a mean of 106 gallons of gas per race with a standard deviation of 6 gallons. If 33 racing cars are randomly selected, what is the probability that the sample mean would be greater than 103.7 gallons? Round your answer to four decimal places.

Respuesta :

Answer:

The probability is  [tex]P(\= X  > 103.7  )  =   0.9862 [/tex]

Step-by-step explanation:

From the question we are told that

  The population mean is  [tex]\mu =  106 \  gallons[/tex]

   The population standard deviation is  [tex]\sigma  =  6 \ gallons[/tex]

    The sample size is  [tex]n  =  33[/tex]

   

Generally the standard deviation of sample mean is mathematically represented as  

        [tex]\sigma_{x} = \frac{\sigma }{\sqrt{n} }[/tex]

=>      [tex]\sigma_{x} = \frac{6}{\sqrt{33} }[/tex]

=>      [tex]\sigma_{x} = 1.044[/tex]

Generally the probability that the sample mean would be greater than 103.7 gallons is mathematically represented as

        [tex]P(\= X  > 103.7  )  =  P(\frac{X - \mu }{\sigma_{x}} > \frac{103.7  -  106}{1.044 }  )[/tex]

Generally  [tex]\frac{X - \mu }{\sigma_{x}}  =  Z (The \  standardized \  value \  of  \= X )[/tex]

So

[tex]P(\= X  > 103.7  )  =  P(Z > -2.203 )[/tex]

From the z table  the probability of (Z > -2.203 ) is  

     [tex]P(Z > -2.203 ) = 0.9862[/tex]

So

    [tex]P(\= X  > 103.7  )  =   0.9862 [/tex]