Complete Question
The complete question is shown on the first uploaded image
Answer:
a i
[tex]P(X < 185 ) = 0.3085 [/tex]
a ii
[tex]P(X > 195 ) = 0.3085 [/tex]
a iii
[tex]P(185 < X < 195 ) = 0.3829 [/tex]
b
[tex]x = 208.8[/tex]
Step-by-step explanation:
From the question we are told that
The mean is [tex]\mu = 190[/tex]
The standard deviation is [tex]\sigma = 10[/tex]
Generally the probability is less than 185 is mathematically represented as
[tex]P(X < 185 ) = P(\frac{X - \mu }{\sigma } < \frac{185 - 190 }{10 } )[/tex]
Generally [tex]\frac{X - \mu }{\sigma } = Z (The \ standardized \ value \ \ of \ X)[/tex]
=> [tex]P(X < 185 ) = P(Z< -0.5)[/tex]
From the z-table the p value of (Z< -0.5) is
[tex]P(Z< -0.5) = 0.3085[/tex]
So
[tex]P(X < 185 ) = 0.3085 [/tex]
Generally the probability is less than 185 is mathematically represented as
[tex]P(X > 195 ) = P(\frac{X - \mu }{\sigma } > \frac{195 - 190 }{10 } )[/tex]
=> [tex]P(X > 195 ) = P(Z > 0.5)[/tex]
From the z-table the p value of (Z > 0.5) is
[tex]P(Z > 0.5) = 0.3085[/tex]
So
[tex]P(X > 195 ) = 0.3085 [/tex]
Generally the probability is less than 185 is mathematically represented as
[tex]P(185 < X < 195 ) = P( \frac{185 - 190 }{10 } < \frac{X - \mu }{\sigma } < \frac{195 - 190 }{10 } )[/tex]
=> [tex]P(185 < X < 195 ) = P(-0.5 < Z > 0.5)[/tex]
=> [tex]P(185 < X < 195 ) = P(Z < 0.5 ) - P(Z < -0.5) [/tex]
From the z-table the p value (Z < 0.5) and (Z < -0.5) is
[tex]P(Z < 0.5) = 0.6915 [/tex]
and
[tex]P(Z < - 0.5) = 0.3085[/tex]
So
=> [tex]P(185 < X < 195 ) = 0.6915 - 0.3085 [/tex]
=> [tex]P(185 < X < 195 ) = 0.3829 [/tex]
Generally the level of cholesterol the 97th percentile represents is mathematically evaluated as
[tex]P(X < x ) = 0.97[/tex]
=> [tex]P(X < x ) = P(\frac{X - \mu}{\sigma } < \frac{x - 190}{10 } ) = 0.97[/tex]
=> [tex]P(X < x ) = P(Z < \frac{x - 190}{10 } ) = 0.97[/tex]
From the z-table the z-score for 0.97 is
[tex]z-score = 1.88[/tex]
=>
[tex]\frac{x - 190}{10 } = 1.88[/tex]
=>[tex]x = 208.8[/tex]
