The life of light bulbs is distributed normally. The variance of the lifetime is 625 and the mean lifetime of a bulb is 570 hours. Find the probability of a bulb lasting for at least 599 hours. Round your answer to four decimal places.
Variance = 625
Standard deviation = Sqrt(625) = 25
z score normal distibution formula:
z = (x - μ) / σ
z = (599-570)/25 = 1.16
P(Z < 1.16) = 0.8770
The probability of a bulb lasting for at least 599 hours is 0.8770
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