Question 668363: Laboratory tests of bacterial counts are often used for declaring a water source "polluted". Suppose that the distribution of bacterial counts in a sample taken from a certain lake is normally distributed with a variance of 9,000,000. Suppose 25 water samples were taken over the course of july 2004 and yielded a mean count of 12,000. Construct an 80% confidence interval estimate of the unknown mean bacterial count in this lake at this time.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Laboratory tests of bacterial counts are often used for declaring a water source "polluted".
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Suppose that the distribution of bacterial counts in a sample taken from a certain lake is normally distributed with a variance of 9,000,000.
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Suppose 25 water samples were taken over the course of july 2004 and yielded a mean count of 12,000.
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Construct an 80% confidence interval estimate of the unknown mean bacterial count in this lake at this time.
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x-bar = 12,000
ME = 1.2816 * [sqrt[9000000/25] = 768.93
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80% CI: 12,000 -768.93 < u < 12000 +768.93
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Cheers,
Stan H.
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