Are these data good evidence that on average the E. coli levels in these swimming areas were safe? Let ?� represent the mean E. coli counts for all possible 100-mL100-mL samples taken from all swimming areas in Erie County. Identify the null and alternative hypotheses. Find the ?� statistic. Give your answer to two decimal places. ?= Find the ?-value�-value . Give your answer to four decimal places. ?-value:
To investigate water quality, in early September 2016, the Ohio Department of Health took water samples at 2424 beaches on Lake Erie in Erie County. Those samples were tested for fecal coliform, which are the E. coli bacteria found in human and animal feces. An unsafe level of fecal coliform means there is a higher chance that disease‑causing bacteria are present and more risk that a swimmer will become ill if she or he should accidentally ingest some of the water. Ohio considers it unsafe for swimming if a 100-milliliter100-milliliter sample (about 3.3 ounces)3.3 ounces) of water contains more than 400400 coliform bacteria. The E. coli levels found by the laboratories are shown in the table.
| 18.7 | 579.4 | 1986.3 | 517.2 | 98.7 | 45.7 | 124.6 | 201.4 |
| 19.9 | 83.6 | 365.4 | 307.6 | 285.1 | 152.9 | 18.7 | 151.5 |
| 365.4 | 238.2 | 209.8 | 290.9 | 137.6 | 1046.2 | 127.4 | 224.7 |
Take these water samples to be an SRS of the water in all swimming areas in Erie County.
Are these data good evidence that on average the E. coli levels in these swimming areas were safe? Let ?� represent the
Identify the null and alternative hypotheses.
Find the ?� statistic. Give your answer to two decimal places.
Find the ?-value�-value . Give your answer to four decimal places.
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