Answer:
The minimum guaranteed mileage is [tex]x = 71489.55[/tex]
Step-by-step explanation:
From the question we are told that
The mean is [tex]\mu = 67900[/tex]
The standard deviation is [tex]\sigma = 2050[/tex]
Generally for the probability to be 4% the minimum guaranteed mileage is evaluated as
[tex]P( X \ge x ) =1- P( \frac{X - \mu }{\sigma } < \frac{ x - 67900 }{ 2050} ) = 0.04[/tex]
[tex]\frac{X -\mu}{\sigma } = Z (The \ standardized \ value\ of \ X )[/tex]
[tex]P( X \ge x ) =1- P( Z<z) = 0.04[/tex]
=> [tex]P( X \ge x ) = P( Z<z) = 0.96[/tex]
=> [tex]z = \frac{ x - 67900 }{ 2050}[/tex]
From the z table, the critical value corresponding to 0.96 to the left of the curve is
[tex]z = 1.751[/tex]
So
[tex]1.751 = \frac{ x - 67900 }{ 2050}[/tex]
=> [tex]x = 71489.55[/tex]
