The Environmental Protection Agency (EPA) warns communities when their tap water is contaminated with too much lead. Drinking water is considered unsafe if the mean concentration of lead is 15.1 parts per billion or greater. The EPA would like to conduct a hypothesis test at the 1% level of significance to determine whether there is significant evidence that the tap water in one particular community is safe. They randomly select 20 water samples from the community and find out a mean lead concentration of 14.61 parts per billion. Lead concentrations in the community are known to follow a normal distribution wtih standard deviation 2.31 parts per billion.
What is the appropriate conclusion for this test?
- Reject the null hypothesis. There is sufficient evidence that the water is safe.
-Fail to reject the null hypothesis. There is sufficient evidence that the water is unsafe.
-Reject the null hypothesis. There is insufficient evidence that the water is safe.
-Reject the null hypothesis. There is sufficient evidence that the water is unsafe.
-Fail to reject the null hypothesis. There is insufficient evidence that the water is unsafe.
-Fail to reject the null hypothesis. There is sufficient evidence that the water is safe.
-Reject the null hypothesis. There is insufficient evidence that the water is unsafe.
-Fail to reject the null hypothesis. There is insufficient evidence that the water is safe.