Question 575691: . An electrical firm manufactures light bulbs that have a length of life that is normally distributed with mean equal to 800 hours and standard deviation of 40 hours. Find the probability that a bulb burns between 778 and 834 hours.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! An electrical firm manufactures light bulbs that have a length of life that is normally distributed with mean equal to 800 hours and standard deviation of 40 hours. Find the probability that a bulb burns between 778 and 834.
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Using z-calculations:
z(778) = (778-800)/40 = -0.55
z(834) = (834-800)/40 = 0.85
P(778<= x <=834) = P(-0.55<= z <=0.85) = normalcdf(-0.55,0.85) = 0.5112
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Using a TI-84:
normalcdf(778,834,800,40) = 0.5112
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Cheers,
Stan H.
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