SOLUTION: Replacement times for CD players are normally distributed with a mean of 7.1 years and a standard deviation of 1.4 years. Find the probability that a randomly selected CD play

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Question 449184: Replacement times for CD players are normally distributed with a mean of 7.1 years and a standard deviation of 1.4 years.
Find the probability that a randomly selected CD player will have a replacement time that exceeds 10 years.

Find the probability that a randomly selected CD player will have a replacement time of between 5 years and 7.1 years.

Two percent of all CD players are replaced in less than how many years?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Replacement times for CD players are normally distributed with a mean of 7.1 years and a standard deviation of 1.4 years.
Find the probability that a randomly selected CD player will have a replacement time that exceeds 10 years.
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z(10) = (10-7.1)/1.4 = 2.0714
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P(x > 10) = P(z > 2.0714) = 0.01916
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Find the probability that a randomly selected CD player will have a replacement time of between 5 years and 7.1 years.
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z(7.1) = 0
z(5)= (5-7.1)/1.4 = -1.5
P(5< x <7.1) = P(-1.5< z <0) = 0.4332
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Two percent of all CD players are replaced in less than how many years?
Find the z-value with a left tail of 2%.
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invNorm(0.02) = -2.0537
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Find the corresponding "year" value using x = zs+u
year = -2.0537*1.4+7.1 = 4.22 years
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Cheers,
Stan H.