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Expert: - 9/25/2011


Question
strength tests carried out on samples of two yarns spun count  gave the following results:          YARN A:  number of sample 4, sample mean 50, sample variance 42 YARN B: number of sample 9, sample mean 42, sample variance 56.          The strengths are expressed in pounds. Does the difference in mean strengths indicate a real difference in the mean strengths of the yarn?

Answer
No, it doesn't, since A and B are closer than the variance say is really small.
For the first one, the mean is 50, and the variance divided by n-1, which is 3.
Now 42/3 = 14, and the means are closer than that

For the seond one, the mean is 56, so 56/(9-1) = 7.
The means of A is just over one standard devition from the mean of B, so this is still not signifcant enough.

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Scott A Wilson

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I can answer any question in general math, arithetic, discret math, algebra, box problems, geometry, filling a tank with water, trigonometry, pre-calculus, linear algebra, complex mathematics, probability, statistics, and most of anything else that relates to math. I can even tell you it takes me over 2,000 steps to go a mile, but is that relevant?

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I earned high honors in both my BS degree and MS degree from Oregon State. I was in near the top in most of my classes. In several classes in mathematics, I was first. In a class of over 100 students, I was always one of the first ones to complete the test. I graduated with well over 50 credits in upper division mathematics.

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