Emissions of sulfur dioxide by industry set off chemical changes in the atmosphe

Question

Emissions of sulfur dioxide by industry set off chemical changes in the atmosphere that result in "acid rain." The acidity of liquids is measured by pH on a scale of 0 to 14. Distilled water has pH 7.0, and lower pH values indicate acidity. Normal rain is somewhat acidic, so acid rain is sometimes defined as rainfall with a pH below 5.0. Suppose that pH measurements of rainfall on different days in a Canadian forest follow a Normal distribution with standard deviation 0.6. A sample of n days finds that the mean pH is x-4.8. Is this good evidence that the mean pH for all rainy days is less than 5.0? The answer depends on the size of the sample. Either by hand or using the P-Value of a Test of Significance applet, carry out four tests of Hai

Explanation / Answer

a)as test statistic z =(X-mean)/std error)

and p value =P(Z<z)

therefore from above:

b)

as sample size increases Xbar becmes more significant.

n p value 4 0.2525 16 0.0912 36 0.0228 81 0.0013

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