Periodically, the county Water Department tests the drinking water at its water distribution center. The lead...

Periodically, the county Water Department tests the drinking water at its water distribution center. The lead levels (parts per billion or ppb) for 10 recent samples are shown below.

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Officials want to determine if the median lead level exceeds the EPA action level of 15 ppb. They are unwilling to make any assumptions about the distribution of lead levels. Help them by conducting an appropriate distribution-free test.

(1) The observed value of the test statistic is
(2) The p-value is (to 4 decimal places)
(3) Does the test reject the null hypothesis at the 0.01 level?

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Expert Solution

(1) The observed value of the test statistic is 14 positive sign and 4 negative sign
(2) The p-value is (to 4 decimal places) = 0.9962
(3) Does the test reject the null hypothesis at the 0.01 level? No. not rejected.

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