Question

Unfortunately, arsenic occurs naturally in some ground water†. A mean arsenic level of μ = 8.0...

Unfortunately, arsenic occurs naturally in some ground water†. A mean arsenic level of μ = 8.0 parts per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested on a regular basis for arsenic. A random sample of 31 tests gave a sample mean of x = 7.0 ppb arsenic, with s = 2.2 ppb. Does this information indicate that the mean level of arsenic in this well is less than 8 ppb? Use α = 0.01.

(a) What sampling distribution will you use? Explain the rationale for your choice of sampling distribution.

a. The Student's t, since the sample size is large and σ is unknown.

b. The standard normal, since the sample size is large and σ is unknown.

c. The Student's t, since the sample size is large and σ is known.

d. The standard normal, since the sample size is large and σ is known.

(b)What is the value of the sample test statistic? (Round your answer to three decimal places.)

(c) Estimate the P-value. P-value > 0.250 0.100 < P-value < 0.250 0.050 < P-value < 0.100 0.010 < P-value < 0.050 P-value < 0.010

(d) Based on your answers in parts (a) to (c), will you reject or fail to reject the null hypothesis?

Are the data statistically significant at level α?

a. At the α = 0.01 level, we reject the null hypothesis and conclude the data are statistically significant.

b. At the α = 0.01 level, we reject the null hypothesis and conclude the data are not statistically significant.

c. At the α = 0.01 level, we fail to reject the null hypothesis and conclude the data are statistically significant.

d. At the α = 0.01 level, we fail to reject the null hypothesis and conclude the data are not statistically significant.

Homework Answers

Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
Unfortunately, arsenic occurs naturally in some ground water†. A mean arsenic level of μ = 8.0...
Unfortunately, arsenic occurs naturally in some ground water†. A mean arsenic level of μ = 8.0 parts per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested on a regular basis for arsenic. A random sample of 31 tests gave a sample mean of x = 7.0 ppb arsenic, with s = 2.2 ppb. Does this information indicate that the mean level of arsenic in this well...
Unfortunately, arsenic occurs naturally in some ground water†. A mean arsenic level of μ = 8.0...
Unfortunately, arsenic occurs naturally in some ground water†. A mean arsenic level of μ = 8.0 parts per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested on a regular basis for arsenic. A random sample of 41 tests gave a sample mean of x = 6.9 ppb arsenic, with s = 2.8 ppb. Does this information indicate that the mean level of arsenic in this well...
Unfortunately, arsenic occurs naturally in some ground water†. A mean arsenic level of μ = 8.0...
Unfortunately, arsenic occurs naturally in some ground water†. A mean arsenic level of μ = 8.0 parts per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crops. This well is tested on a regular basis for arsenic. A random sample of 41 tests gave a sample mean of x = 7.0 ppb arsenic, with s = 2.4 ppb. Does this information indicate that the mean level of arsenic in this well...
A random sample of 41 adult coyotes in a region of northern Minnesota showed the average...
A random sample of 41 adult coyotes in a region of northern Minnesota showed the average age to be x = 2.09 years, with sample standard deviation s = 0.88 years. However, it is thought that the overall population mean age of coyotes is μ = 1.75. Do the sample data indicate that coyotes in this region of northern Minnesota tend to live longer than the average of 1.75 years? Use α = 0.01. (a) What is the level of...
Weatherwise is a magazine published by the American Meteorological Society. One issue gives a rating system...
Weatherwise is a magazine published by the American Meteorological Society. One issue gives a rating system used to classify Nor'easter storms that frequently hit New England and can cause much damage near the ocean. A severe storm has an average peak wave height of μ = 16.4 feet for waves hitting the shore. Suppose that a Nor'easter is in progress at the severe storm class rating. Peak wave heights are usually measured from land (using binoculars) off fixed cement piers....
Weatherwise is a magazine published by the American Meteorological Society. One issue gives a rating system...
Weatherwise is a magazine published by the American Meteorological Society. One issue gives a rating system used to classify Nor'easter storms that frequently hit New England and can cause much damage near the ocean. A severe storm has an average peak wave height of μ = 16.4 feet for waves hitting the shore. Suppose that a Nor'easter is in progress at the severe storm class rating. Peak wave heights are usually measured from land (using binoculars) off fixed cement piers....
A random sample of 51 adult coyotes in a region of northern Minnesota showed the average...
A random sample of 51 adult coyotes in a region of northern Minnesota showed the average age to be x = 2.03 years, with sample standard deviation s = 0.80 years. However, it is thought that the overall population mean age of coyotes is μ = 1.75. Do the sample data indicate that coyotes in this region of northern Minnesota tend to live longer than the average of 1.75 years? Use α = 0.01. (a) What is the level of...
Weatherwise is a magazine published by the American Meteorological Society. One issue gives a rating system...
Weatherwise is a magazine published by the American Meteorological Society. One issue gives a rating system used to classify Nor'easter storms that frequently hit New England and can cause much damage near the ocean. A severe storm has an average peak wave height of μ = 16.4 feet for waves hitting the shore. Suppose that a Nor'easter is in progress at the severe storm class rating. Peak wave heights are usually measured from land (using binoculars) off fixed cement piers....
Unfortunately, arsenic occurs naturally in some ground water (Reference: Union Carbide Technical Report). A mean arsenic...
Unfortunately, arsenic occurs naturally in some ground water (Reference: Union Carbide Technical Report). A mean arsenic level of 8 parts per billion (ppb) is considered safe for agricultural use. A well in Texas is used to water cotton crop. This well is tested on a regular basis for arsenic. A random sample of 37 tests gave a sample mean of 7.2. Given that the standard deviation of arsenic level is 1.9, does this information indicate that the mean level of...
Let x be a random variable that represents the pH of arterial plasma (i.e., acidity of...
Let x be a random variable that represents the pH of arterial plasma (i.e., acidity of the blood). For healthy adults, the mean of the x distribution is μ = 7.4.† A new drug for arthritis has been developed. However, it is thought that this drug may change blood pH. A random sample of 41 patients with arthritis took the drug for 3 months. Blood tests showed that x = 8.6 with sample standard deviation s = 3.2. Use a...