A researcher surveys middle-school students on their study habits. She finds that in a random sample of 28 middle-school students, the mean amount of time that they spend working on the computer each night is 2.4 hours with a standard deviation of 0.92 hours. She uses the sample statistics to compute a 95% confidence interval for the population mean - the the mean amount of time that all middle-school students spend working on the computer each night. What is the margin of error for this confidence interval

Respuesta :

Answer:

The margin of error is  [tex]E = 1.96 * \frac{ 0.92}{\sqrt{28 } }[/tex]

Step-by-step explanation:

From the question we are told that

    The sample size is  [tex]n = 28[/tex]

     The  sample  mean is  [tex]\= x = 2.4 \ hr[/tex]

      The  standard deviation is  [tex]\sigma = 0.92 \ hr[/tex]

     

Given that the confidence level is 95% the the level of significance can be evaluated as

             [tex]\alpha = 100 -95[/tex]

            [tex]\alpha = 5 \%[/tex]

             [tex]\alpha = 0.05[/tex]

Next we obtain the critical value of  [tex]\frac{\alpha }{2}[/tex] from the normal distribution table,the value is  [tex]Z_{\frac{\alpha }{2} } = Z_{\frac{0.05}{2} } = 1.96[/tex]

Generally the margin of error is mathematically represented as

           [tex]E = Z_{\frac{\alpha }{2} } * \frac{\sigma }{\sqrt{n} }[/tex]

substituting values

          [tex]E = 1.96 * \frac{ 0.92}{\sqrt{28 } }[/tex]

         [tex]E = 0.3408[/tex]

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