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Hush193 · May 14, 2008, 07:57 AM

Hi,

I have the following question and do not know where to look for an answer:

Historical data indicates that the diameter of a ball bearing is normally distributed with a mean of 0.525 cm and a standard deviation of 0.008 cm. Suppose that a sample of 16 ball bearings are randomly selected from a very large lot. Determine the probability that the average diameter of a ball bearing is greater than 0.530 cm.

Any help is appreciated.

Thanks! :)

galactus · May 14, 2008, 08:05 AM

Use the formula $z=\frac{(x-{\mu})\sqrt{n}}{\sigma}$ to find the z-score corresponding, then look it up in a z-table.

Remember, you want greater than, so subtract from 1.