Arsenic occurs naturally in some ground water and can be toxic. A mean arsenic level of μ=9μ=9 parts per billion (ppb) is considered safe for agricultural use. A well in San Bernardino County is used to water strawberry crops. This well is tested on a regular basis for arsenic. A random sample of 46 tests gave a sample mean of 8 ppb arsenic, with a sample standard deviation of 5.4 ppb. Does this information indicate that the mean level of arsenic in this well is different from μ=9μ=9 ppb? Use α=0.05α=0.05 What is the level of significance? State the null and alternate hypotheses. H0:H0:? χ p σ μ Select an answer < ≠ > = ppb H1:H1:? σ p χ μ Select an answer ≠ > < = ppb What sampling distribution will you use? Explain the rationale for you choice of sampling distribution. The Student's t, since we have a simple random sample that is large and σσ is known. The Student's t, since we have a simple random sample that is large. The standard normal, since we have a simple random sample that is large and σσ is known. The standard normal, since we have a simple random sample that is large. What is the value of the test statistic? (Round your answer to two decimal places.) Find the P-value. (Round your answer to four decimal places.) Based on your results, will you reject or fail to reject the null hypothesis? Are the data statistically significant at level αα? At the α=0.05α=0.05 level, we reject the null hypothesis and conclude the data are not statistically significant. At the α=0.05α=0.05 level, we reject the null hypothesis and conclude the data are statistically significant. At the α=0.05α=0.05 level, we fail to reject the null hypothesis and conclude the data are not statistically significant. At the α=0.05α=0.05 level, we fail to reject the null hypothesis and conclude the data are statistically significant. Interpret your conclusion in the context of the application. There is insufficient evidence at the 0.05 level to conclude that the mean level of arsenic in the well is different from 9 ppb. There is sufficient evidence at the 0.05 level to conclude that the mean level of arsenic in the well is different from 9 ppb.
Arsenic occurs naturally in some ground water and can be toxic. A mean arsenic level of μ=9μ=9 parts per billion (ppb) is considered safe for agricultural use. A well in San Bernardino County is used to water strawberry crops. This well is tested on a regular basis for arsenic. A random sample of 46 tests gave a sample mean of 8 ppb arsenic, with a sample standard deviation of 5.4 ppb. Does this information indicate that the mean level of arsenic in this well is different from μ=9μ=9 ppb? Use α=0.05α=0.05
What is the level of significance?
State the null and alternate hypotheses.
H0:H0:? χ p σ μ Select an answer < ≠ > = ppb
H1:H1:? σ p χ μ Select an answer ≠ > < = ppb
What sampling distribution will you use? Explain the rationale for you choice of sampling distribution.
- The Student's t, since we have a simple random sample that is large and σσ is known.
- The Student's t, since we have a simple random sample that is large.
- The standard normal, since we have a simple random sample that is large and σσ is known.
- The standard normal, since we have a simple random sample that is large.
What is the value of the test statistic? (Round your answer to two decimal places.)
Find the P-value. (Round your answer to four decimal places.)
Based on your results, will you reject or fail to reject the null hypothesis? Are the data statistically significant at level αα?
- At the α=0.05α=0.05 level, we reject the null hypothesis and conclude the data are not statistically significant.
- At the α=0.05α=0.05 level, we reject the null hypothesis and conclude the data are statistically significant.
- At the α=0.05α=0.05 level, we fail to reject the null hypothesis and conclude the data are not statistically significant.
- At the α=0.05α=0.05 level, we fail to reject the null hypothesis and conclude the data are statistically significant.
Interpret your conclusion in the context of the application.
- There is insufficient evidence at the 0.05 level to conclude that the mean level of arsenic in the well is different from 9 ppb.
- There is sufficient evidence at the 0.05 level to conclude that the mean level of arsenic in the well is different from 9 ppb.
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