SOLUTION: A Christmas tree light has an expected life of 200 hr and a standard deviation of 2 hr.
(a) Find a bound on the probability that one of these Christmas tree lights will require re
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(a) Find a bound on the probability that one of these Christmas tree lights will require re
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Question 940214: A Christmas tree light has an expected life of 200 hr and a standard deviation of 2 hr.
(a) Find a bound on the probability that one of these Christmas tree lights will require replacement between 190 hr and 210 hr. (Enter your answer to two decimal places.)
at least
(b) Suppose a large city uses 130,000 of these Christmas tree lights as part of its Christmas decorations. Estimate the number of lights that are likely to require replacement between 180 hr and 220 hr of use.
lights Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! A Christmas tree light has an expected life of 200 hr and a standard deviation of 2 hr.
(a) Find a bound on the probability that one of these Christmas tree lights will require replacement between 190 hr and 210 hr. (Enter your answer to two decimal places.)
at least
z(190) = (190-200)/2 = -10/2 = -5
z(210) = (210-200)/2 = 10/2 = 5
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p(190< x <210) = P(-5< z <5) = 1.00 (using a TI-84)
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(b) Suppose a large city uses 130,000 of these Christmas tree lights as part of its Christmas decorations. Estimate the number of lights that are likely to require replacement between 180 hr and 220 hr of use.
P(180< x <220) = p(-10< z < 10) = 1
Ans:: All of them
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Question:: Are you sure you posted the correct standard deviation?
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Cheers,
Stan H.
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