A farmer investigated pesticide contamination at a small pond with significant r

Question

A farmer investigated pesticide contamination at a small pond with significant run-off (meaning water runs from the nearby fields into the pond). Eight measurements of pesticide concentrations were randomly taken at the pond (assume the pesticide is normally distributed throughout the pond). The reported pesticide concentrations: 15.1, 13.2, 15.3, 14.7, 11.0, 15.2, 16.5, 18.1, g/L. Given that the data distribution is normal, find the t-value for a 95% confidence level.

Question 11 options:

A farmer investigated pesticide contamination at a small pond with significant run-off (meaning water runs from the nearby fields into the pond). Ten measurements of pesticide concentrations were randomly taken at the pond (assume the pesticide is normally distributed throughout the pond). The reported pesticide concentrations: 18.4, 25.8, 27.3, 19.5, 23.8, 29.4, 30.1, 29.1, 33.8 and 35.7 g/L. Given that the data distribution is normal, find the t-value for a 90% confidence level.

Question 12 options:

Which of the following is true about the t-distribution?

Question 13 options:

A farmer investigated pesticide contamination at a small pond with significant run-off (meaning water runs from the nearby fields into the pond). Eight measurements of pesticide concentrations were randomly taken at the pond (assume the pesticide is normally distributed throughout the pond). The reported pesticide concentrations: 15.1, 13.2, 15.3, 14.7, 11.0, 15.2, 16.5, 18.1 g/L. Given that the data distribution is normal, find the t-value for a 90% confidence level.

Question 14 options:

Which of the following statements is not true regarding a robust statistic:

Question 15 options:

The margin of error is a calculation that describes the error introduced into a study when the sample isn't truly random.

Question 2 options:

When doing significance tests for two proportions we can pool our estimates to compute the standard error because the null hypothesis assumes the two sample proportions are equal.

Question 3 options:

The formula for the test statistic for a one-sample significance test of a population proportion is

Question 4 options:

False

A political poll of Canadians was conducted to investigate their opinions on gun control. Each person was asked if they were in favor or gun control or not in favor of gun control - non respondents were removed from the results. The survey found that 25% of people contacted were not in favor of gun control laws. These results were accurate to within 3 percentage points, 19 times out of 20. Which of the following is NOT CORRECT?

Question 5 options:

The 95% confidence interval is approximately from (22% to 28%).

We are 95% confident that the true proportion of people not in favor is within 3 percentage points of 25%.

In approximately 95% of polls on this issue, the confidence interval will include 25%.

If another poll of similar size were taken, the percentage of people IN FAVOR of gun control would likely range from 72% to 78%.

A properly designed poll of the same size in the United States would have the same margin of error.

Suppose a researcher is interested in estimating the difference between the proportion of errors in the local newspaper during the week and the proportion of errors in the weekend editions. What is the 95% confidence interval for the difference in the proportion of errors? Assume the populations are independent and the samples are randomly taken where the number of pages sampled is n and the number of errors found is x.
Sample 1 for the week:  n1 = 500   x1 = 125
Sample 2 for the weekend:  n2 = 200    x2 = 70

a) 2.306 b) 2.365 c) 1.860 d) 1.895 e) None of the above p-P

Explanation / Answer

11)
n = 8 , df = n - 1 = 8 - 1 = 7
t value at 95% CI = 2.365
Answer is option b)

12)

n = 10 , df= n -1 = 10 - 1 = 9
t value at 90% CI = 1.383

14)
n = 8 , df = n - 1 = 8 - 1 = 7
t value at 90% CI = 1.895
Answer is option c)

4) The formula for the test statistic for a one-sample significance test of a population proportion is true

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