SOLUTION: the life span of a battery is normally distributed, with a mean of 2100 hours and a standard deviation of 50 hours. what percent of batteries have a life span that is more than 217

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Question 800087: the life span of a battery is normally distributed, with a mean of 2100 hours and a standard deviation of 50 hours. what percent of batteries have a life span that is more than 2170 hours? would it be unusual for a battery to have a life span that is more than 2170 hours? explain your reasoning.
Answer by stanbon(75887) About Me  (Show Source):
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the life span of a battery is normally distributed, with a mean of 2100 hours and a standard deviation of 50 hours. what percent of batteries have a life span that is more than 2170 hours? would it be unusual for a battery to have a life span that is more than 2170 hours? explain your reasoning.
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z(2170) = (2170-2100)/50 = 70/50 = 1.4
P(x > 2170) = P(z > 1.4) = binomcdf(1.4,100) = 0.0808
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Not unusual. 2170 is not greater than 2 standard deviations
above the mean.
Cheers,
Stan H.