Respuesta :

Answer:

The percentage is  [tex]P(0.09 < \mu < 1.2 ) = 34.9\%[/tex]

Step-by-step explanation:

From the question we are told that

  The random number is  [tex]x_1 = 0.09 \ and \ x_2 = 1.2[/tex]

Generally the mean of standard normal distribution is  [tex]\mu = 0[/tex]

                 The  standard deviation of a standard normal distribution is  [tex]\sigma = 1[/tex]

The percentage of the data in a standard normal distribution lies between

  [tex]x_1 = 0.09 \ and \ x_2 = 1.2[/tex] is mathematically represented as

       [tex]P(x_1 < \mu < x_2 ) = P(\frac{x_1 - \mu}{\sigma } <\frac{X - \mu}{\sigma } < \frac{x_2 - \mu}{\sigma } )[/tex]

      [tex]P(0.09 < \mu < 1.2 ) = P(\frac{0.09 - 0}{1 } <\frac{X - \mu}{\sigma } < \frac{1.2 - 0}{1 } )[/tex]

      [tex]P(0.09 < \mu < 1.2 ) = P(0.09 <\frac{X - \mu}{\sigma } < 1.2 )[/tex]

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

      [tex]P(0.09 < \mu < 1.2 ) = P(0.09 <Z < 1.2 )[/tex]

      [tex]P(0.09 < \mu < 1.2 ) = P (Z < 1.2 )- P( Z<0.09)[/tex]

From the z-table  

      [tex]P (Z < 1.2 )= 0.88493[/tex]

      [tex]P( Z<0.09) = 0.53586[/tex]

So

    [tex]P(0.09 < \mu < 1.2 ) = 0.88493 - 0.53586[/tex]

    [tex]P(0.09 < \mu < 1.2 ) = 0.349[/tex]

Hence the percentage  is  

     [tex]P(0.09 < \mu < 1.2 ) = 34.9\%[/tex]