If 51% of a population will vote for Candidate A in an election, what is the probability that in a random sample of 75 voters, fewer than 50% of the sample will vote for Candidate A

Respuesta :

Answer:

The value is   [tex]P(X < 0.50 ) = 0.43133[/tex]

Step-by-step explanation

From the question we are told that

    The population proportion is  p =  0.51

     The sample size is  n  =  75

Generally given that the sample size is large enough (i.e n > 30) the mean of this sampling distribution is mathematically represented as

            [tex]\mu_x = p = 0.5 1[/tex]

Generally the standard deviation of this sample distribution is mathematically represented as

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

=>          [tex]\sigma = \sqrt{\frac{0.51 (1- 0.51 )}{75} }[/tex]

=>          [tex]\sigma = 0.058[/tex]

Generally the probability that in a random sample of 75 voters, fewer than 50% of the sample will vote for Candidate A is mathematically represented as

          [tex]P(X < 0.50 ) = P( \frac{ X - \mu_x }{\sigma } < \frac{ 0.50 - 0.51 }{0.0578 } )[/tex]

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

=>       [tex]P(X < 0.50 ) = P( Z < -0.1730 )[/tex]

From the z table  the area under the normal curve to the left corresponding to   -0.1720  is

        [tex]P( Z < -0.1730 ) = 0.43133[/tex]

So

         [tex]P(X < 0.50 ) = 0.43133[/tex]