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The level of dissolved oxygen (DO) in a river is an important indicator of the water's ability to support aquatic life. A researcher measures the DO level at 30 randomly

chosen locations along a river. The sample mean was 8.22 mg/L, with an associated 95% confidence interval for u from 6.35 mg/L to 10.09 mg/L. Of the following options, which one is the best interpretation of that confidence interval?

Question 2

The following data represents the lengths of time, in minutes, that 6 patients waited in a doctor's office before receiving treatment:

6, 11, 9, 5, 10, 15

What is the value of the standard error of the sample mean obtained from this data?

Question 3

To conduct the pooled variance t-test, which assumptions are required?

Question 4

Suppose birth weight of a newborn follows a normal distribution with mean 3kg. If the researcher assumes a = 1.6kg (based on previous information), what minimum sample size is required so that the sample mean will be within 0.4kg of its population mean, with 95% confidence?

Question 5

Iris setosa is a species of iris whose petal length is known to follow a normal distribution. A random sample of 16 flowers were obtained. A researcher wished to test if the petal length of iris setosa is 6.5 cm (two-sided test). Assume the value of the test statistic had come out to be t = 2.5.

Of the following options, which one is the best conclusion of the test, at the 1% level of significance?

Question 6

Suppose we sample 15 observations from a normally distributed population where o = 10, and we wish to test Ho: μ = 15 against a two-sided alternative. If the sample

mean is 9, what is the p-value of the test?

Question 7

Suppose X follows a standard normal distribution, what is the value of b if P(X>b)=0.3 ?

Question 8

A drug company wishes to examine if their drug is effective in treating high blood pressure. In the study, the researchers randomly selected 18 volunteers and recorded their blood pressure before taking the drugs. After 12 weeks on the drug, the blood pressure was measured again.

Assuming that both populations (before and after the treatment) are normally distributed, what is a 95% confidence interval for the true mean difference (After- Before) in blood pressure?

Question 9

Suppose we randomly sample 12 observations below from a normally distributed population.

31, 20, 6, 7, 11, 18, 14, 9, 22, 29, 30, 7

We want to use this data to calculate a 88% confidence interval for the population mean. What's the value of confidence coefficient we should use to calculate the confidence interval?

Question 10

A study investigated several aspects of the ratio of the lengths of the index finger to the ring finger in women. Suppose we wish to test whether there is a difference

between the true means of the ratio for white and black women.

Which one of the following is the most appropriate symbolic representation of those hypotheses?

Question 11

Researchers were interested in estimating the average water hardness in Guelph, where water hardness was measured by the calcium carbonate concentration in

mg/L. If they carried out a test of Ho: μ-300

against a two-sided alternative at the 5% level of significance, the p-value for this test was found to be 0.0132. Which of the following 95% confidence intervals could

be a 95% confidence interval for the mean water hardness in Guelph?

Question 12

Suppose we draw a random sample of 40 observations from a population with mean u and standard deviation o. Which one of the following statements about the sampling distribution of the sample mean is TRUE?

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