Question 124682: Please kindly help me. I am having problem answering this question. Thank you for your kind assistance.
1) A sample of PVC pipes coming off a production line were tested for pipe diameter size. The statistical results (in millimeters) were:
Mean 300
Median 300
Mode 300
Standard Deviation 15
Range 90
Number in Sample 100
a) According to the Normal Rule, what percent of the pipes had diameters between 285 and 315?
b) What would the range of pipe diameters need to be in order to capture 95% of the pipe diameters?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! A sample of PVC pipes coming off a production line were tested for pipe diameter size. The statistical results (in millimeters) were:
Mean 300
Median 300
Mode 300
Standard Deviation 15
Range 90
Number in Sample 100
a) According to the Normal Rule, what percent of the pipes had diameters between 285 and 315?
That interval is one standard deviation to the left and one to the right
of the mean. The Rule says 68% of the diameters are in that interval.
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b) What would the range of pipe diameters need to be in order to capture 95% of the pipe diameters?
two standard deviations to the right and to the left of the mean
300-2*15 = 270
300+2*15 = 330
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Cheers,
Stan H.
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