Question 977039: The time required to assemble a piece of machinery is a random variable having
approximately a normal distribution with = 13.2 minutes and = 3.0 minutes. What are
the probabilities that the assembly of a piece of machinery of this kind will take
(i) at least 11.1 minutes
(ii) anywhere from 10.35 to 16.05 minutes?
(iii) at most 15.92 minutes
Found 2 solutions by stanbon, FrankM:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The time required to assemble a piece of machinery is a random variable having
approximately a normal distribution with mean = 13.2 minutes and std = 3.0 minutes.
What are the probabilities that the assembly of a piece of machinery of this kind will take
(i) at least 11.1 minutes
z(11.1) = (11.1-13.2)/3 = -2.1/3 = -0.7
P(x >= 11.1) = P(z >= -0.7) = normalcdf(-0.7,100) = 0.7580
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(ii) anywhere from 10.35 to 16.05 minutes?
Find the z-value and determine the propability between them.
Ans normalcdf(10.35,16.05,13.2,3) = 0.6579
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(iii) at most 15.92 minutes
Ans: normalcdf(-100,15.92,13.2,3) = 0,8177
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Cheers,
Stan H.
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Answer by FrankM(1040)  (Show Source):
You can put this solution on YOUR website! Posting the first answer (i) -
11.1 is 2.1 minutes below the median, or 2.1/3 = .7, a Z = -.7
 .
75.8% will be above this number.
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