Use z-scores to determine which score has the highest relative position: a score of 42.5 on a test for which the mean is 47 and standard deviation of 9, or a score of 2.5 on a test for which the mean is 4.2 and the standard deviation is 1.2 , or a score of 427.2 on a test for which the mean is 444 and the standard deviation is 42.

Respuesta :

Answer

a) [tex]\bar{X}=42.5 , \mu = 47 , \sigma = 9[/tex]

     [tex]z_1 = \dfrac{\bar{X}-\mu}{\sigma}[/tex]

     [tex]z_1 = \dfrac{42.5-47}{9}[/tex]

           z₁ = -0.5

b) [tex]\bar{X}=2.5 , \mu = 4.2 , \sigma = 1.2[/tex]

     [tex]z_2 = \dfrac{\bar{X}-\mu}{\sigma}[/tex]

     [tex]z_2= \dfrac{2.5-4.2}{1.2}[/tex]

           z₂ = -1.42

c) [tex]\bar{X}=427.2 , \mu = 444 , \sigma = 42[/tex]

     [tex]z_3 = \dfrac{\bar{X}-\mu}{\sigma}[/tex]

     [tex]z_3 = \dfrac{427.2-444}{42}[/tex]

           z₃ = -0.4

The better relative position score will be more standard deviations above the mean.

Higher the Z-score better is the relative position

hence, z₂ has highest relative position