A survey of all medium- and large-sized corporations showed that of them offer retirement plans to their employees. Let be the proportion in a random sample of such corporations that offer retirement plans to their employees. Find the probability that the value of will be greater than .

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Complete Question

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Answer:

a

 [tex]P(0.51 <  \^ p <  0.61 ) =  0.2587 [/tex]

b

 [tex]P(\^ p > 0.71 ) = 0.15165[/tex]

Step-by-step explanation:

From the question we are told that

   The population proportion  is  [tex]p = 0.64[/tex]  

   The sample size is n =  50

Generally the mean of this sampling distribution is  

       [tex]\mu_{x} = p = 0.64[/tex]

Generally the standard deviation is mathematically represented as

      [tex]\sigma  =  \sqrt{ \frac{p(1- p )}{n } } [/tex]

=>    [tex]\sigma  =  \sqrt{ \frac{0.64(1- 0.64 )}{ 50} } [/tex]

=>    [tex]\sigma  =  0.068  [/tex]

Generally the probability that the value of [tex]\^ p[/tex] will be between 0.54 and 0.61 is mathematically represented as

     [tex]P(0.51 < \^ p < 0.61 ) = P( \frac{0.5 4 - \mu_{x}}{\sigma } < \frac{\^ p- \mu_{x}}{\sigma } < \frac{0.6 1 - \mu_{x}}{\sigma } )[/tex]

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

 [tex]P(0.51 <  \^ p <  0.61 ) =  P( \frac{0.5 4  - 0.64}{0.068 } < Z < \frac{0.6 1  - 0.64}{0.068} )[/tex]

     [tex]P(0.51 <  \^ p <  0.61 ) =  P(-1.470 < Z < -0.4412 )[/tex]

=>   [tex]P(0.51 <  \^ p <  0.61 ) =  P( Z < -0.4412 ) - P(Z <  -1.470 ) [/tex]

From the z table  the probabilities of  ( Z < -0.4412 ) and (Z <  -1.912 ) is

     [tex]P ( Z < -0.4412 )  = 0.32953 [/tex]

and  

    [tex]P(Z < -1.470 ) = 0.070781[/tex]

Generally

   [tex]P(0.51 <  \^ p <  0.61 ) =  0.32953 -0.070781 [/tex]

  [tex]P(0.51 <  \^ p <  0.61 ) =  0.2587 [/tex]

Generally the probability that the value of [tex]\^ p[/tex] will be greater than 0.71  is mathematically represented as

        [tex]P(\^ p > 0.71 ) = P( \frac{\^ p - \mu_{x}}{\sigma} > \frac{0.71 - 0.64 }{ 0.068 } )[/tex]

=>    [tex]P(\^ p > 0.71 ) = P( Z > 1.0294 )[/tex]

From the z table  the probabilities of ( Z >   1.0294  )

      [tex]P( Z > 1.0294 ) = 0.15165[/tex]

So

  [tex]P(\^ p > 0.71 ) = 0.15165[/tex]

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