SOLUTION: Terri Vogel, an amateur motorcycle racer, averages 129.71 seconds per 2.5 mile lap with a standard deviation of 2.28 seconds. The distribution of her race times is normally distrib

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Question 859349: Terri Vogel, an amateur motorcycle racer, averages 129.71 seconds per 2.5 mile lap with a standard deviation of 2.28 seconds. The distribution of her race times is normally distributed.
c.)The middle 80% of her laps are from _______ seconds to _______ seconds.

Answer by stanbon(75887) About Me  (Show Source):
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Terri Vogel, an amateur motorcycle racer, averages 129.71 seconds per 2.5 mile lap with a standard deviation of 2.28 seconds. The distribution of her race times is normally distributed.
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Find the z-value with a left tail of 10%::
invNorm(0.10) = -1.2816
Find the corresponding time value:
Lower limit::::: x = -1.2816*2.28+129.71 = 126.79 seconds
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z-value with a right tail of 10%::
invNorm(0.10) = 1.2816
Upper limit;:::: x = 1.2816*2.28+129.71 = 132.63 seconds
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c.)The middle 80% of her laps are from _______ seconds to _______ seconds
Cheers,
Stan H.
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