The results of a test that follows a normal distribution have a mean value of 10.0 and a standard deviation of 1.
Find the probability that a single reading is between 8 and 10

Respuesta :

Answer:

The value is [tex]P(8 < X < 10 ) = 0.8186[/tex]

Step-by-step explanation:

From the question we are told that

    The mean is  [tex]\mu = 10 .0[/tex]

     The standard deviation is  [tex]\sigma = 1[/tex]

Generally the probability that a single reading is between 8 and 10 is mathematically represented as

      [tex]P(8 < X < 10 ) = P( \frac{8 - 10 }{ 1} < \frac{X - \mu }{ \sigma } < \frac{10 - 10 }{1} )[/tex]

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

=>    [tex]P(8 < X < 10 ) = P( -2 < Z< 1 )[/tex]

=>   [tex]P(8 < X < 10 ) = P( Z< 1 ) - P( Z < -2 )[/tex]

From the z table  the area under the normal curve to the left corresponding to  1 and  -2  is  

       [tex]P( Z< 1 ) = 0.84134[/tex]

and

     [tex]P( Z < -2 ) = 0.02275[/tex]

=>   [tex]P(8 < X < 10 ) = 0.84134 - 0.02275[/tex]

=>   [tex]P(8 < X < 10 ) = 0.8186[/tex]