According to a government study among adults in the 25- to 34-year age group, the mean amount spent per year on reading and entertainment is $1,999. Assume that the distribution of the amounts spent follows the normal distribution with a standard deviation of $574. (Round your z-score computation to 2 decimal places and final answers to 2 decimal places.) What percent of the adults spend more than $2,550 per year on reading and entertainment?

Respuesta :

Answer:

The probability is  [tex]P(X > x ) = 0.19215[/tex]

Step-by-step explanation:

From the question we are told that

   Th The population mean [tex]\mu = \$ 1,999[/tex]

    The  standard deviation is  [tex]\sigma = \$ 574[/tex]

    The  values considered is  [tex]x = \$ 2,500[/tex]

Given that the distribution of the amounts spent follows the normal distribution then the  percent of the adults spend more than $2,550 per year on reading and entertainment is mathematically represented as

    [tex]P(X > x ) = P(\frac{ X - \mu}{\sigma } > \frac{ x - \mu}{\sigma } )[/tex]

Generally  

            [tex]X - \mu}{\sigma } = Z (The \ standardized \ value \ of \ X )[/tex]

So

      [tex]P(X > x ) = P(Z > \frac{ x - \mu}{\sigma } )[/tex]

substituting values

      [tex]P(X > 2500 ) = P(Z > \frac{ 2500 - 1999}{574 } )[/tex]

      [tex]P(X > 2500 ) = P(Z >0.87 )[/tex]

From the normal distribution table the value of [tex]P(Z >0.87 )[/tex] is  

       [tex]P(Z >0.87 ) = 0.19215[/tex]

Thus  

       [tex]P(X > x ) = 0.19215[/tex]

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