SOLUTION: Suppose that the lifespan of a particular type of lightbulb is normally distributed with a mean of 1000 hours and a variance of 8100 hours. Determine the probability that a randoml

Question 409758: Suppose that the lifespan of a particular type of lightbulb is normally distributed with a mean of 1000 hours and a variance of 8100 hours. Determine the probability that a randomly selected lightbulb will last for 800 hours or less?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Suppose that the lifespan of a particular type of lightbulb is normally distributed with a mean of 1000 hours and a variance of 8100 hours. Determine the probability that a randomly selected lightbulb will last for 800 hours or less?
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z(800) = (800-1000)/(8100) = -200/8100 = -2/81
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P(x <= 800) = P(x < -2/81) = normalcdf(-100,-2/81) = 0.4902
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Cheers,
Stan H.
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