the concentration of heaxane 0a common solvent) was measured in units of micrograms per liter for a simple random sample of ninteen specimens of untreated ground water taken near a municipal landfill. the sample mean was 508.4 with a sample standard deviation of 4.3. sixteen specimens of treated ground water had an average hexane concentration of 506.1. with a standard deviation of 4.7. it is responsable to assume that both sample come from populations that are approximately normal. can you conclude that the mean hexane concentration is less in treated water than in untreated water? use the α= 0.01 level of significance.A). yes    B). No

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Asked Nov 18, 2019
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the concentration of heaxane 0a common solvent) was measured in units of micrograms per liter for a simple random sample of ninteen specimens of untreated ground water taken near a municipal landfill. the sample mean was 508.4 with a sample standard deviation of 4.3. sixteen specimens of treated ground water had an average hexane concentration of 506.1. with a standard deviation of 4.7. it is responsable to assume that both sample come from populations that are approximately normal. can you conclude that the mean hexane concentration is less in treated water than in untreated water? use the α= 0.01 level of significance.

A). yes    B). No

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Step 1

The provided information are:

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Sample size (n)19 Sample mean () 508.4 Sample standard deviation (s) 4.3 Sample size (n2)16 Sample mean () 506.1 Sample standard deviation (s2) 4.2 Population variances are assumed to be equal Significance level (a)= 0.01

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Step 2

 The null and alternative hypotheses are:

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= 0 Н.: и — п, <0

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Step 3

The test is left-sided.

The test stati...

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t = 1 1 п, п, where (п -1)s + (п, -1)s, 2 nn-2

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