Question 1

A 95% confidence interval for the difference in means between two populations is given as $$(-2.1, 4.3). $$What does this interval suggest about the difference in the two population means?

Accepted Answer

There is no significant difference between the two population means at the 95% confidence level.

Question 2

Which of the following is NOT part of the 5-number summary of a data set?

Accepted Answer

Mean

Question 3

Given the data set: $$2, 4, 7, 10, 15$$, what is the z-score of the value $$15$$? (Use the sample mean and sample standard deviation.)

Accepted Answer

$$z = \frac{15 - 7.6}{5.13} \approx 1.44$$

Question 4

Which of the following best defines an outlier in a data set?

Accepted Answer

A value that lies more than 1.5 times the interquartile range above the third quartile or below the first quartile.

Question 5

A researcher wants to test if a new medication lowers blood pressure. Express the original claim 'the medication lowers blood pressure' in symbolic form and identify the null and alternative hypotheses.

Accepted Answer

Null: $$H_0$$: \mu \geq \$$mu_0$$; Alternative: $$H_1$$: \mu \u003c \$$mu_0$$

Question 6

Which of the following is a parameter?

Accepted Answer

The mean height of all adult women in the United States.

Question 7

A grouped frequency distribution table has class limits 10-19, 20-29, 30-39, 40-49. What is the class width?

Accepted Answer

$$10$$

Question 8

Which of the following is NOT a requirement for a binomial distribution?

Accepted Answer

The probability of success changes from trial to trial.

Question 9

Which of the following best describes a t-distribution?

Accepted Answer

A symmetric, bell-shaped distribution used when the population standard deviation is unknown and the sample size is small.

Question 10

Which level of measurement is represented by the following data: 'Freshman, Sophomore, Junior, Senior'?

Accepted Answer

Ordinal

Question 11

Which of the following statements about correlation is true?

Accepted Answer

A correlation coefficient close to $$0$$ indicates little to no linear relationship between variables.

Question 12

A sample of home prices contains several extremely high values. Which measure of central tendency is most affected by these outliers?

Accepted Answer

Mean

Question 13

A hospital administrator wants to estimate the average length of stay for patients. Which type of sampling is used if she randomly selects 5 departments and surveys all patients in those departments?

Accepted Answer

Cluster sampling

Question 14

If the variance of a data set is $$16$$, what is the standard deviation?

Accepted Answer

$$4$$

Question 15

Which of the following is a Type I error?

Accepted Answer

Rejecting the null hypothesis when it is actually true.

Question 16

A student rolls a fair die and flips a fair coin. What is the probability of getting a 4 on the die and heads on the coin?

Accepted Answer

$$\frac{1}{12}$$

Question 17

Which of the following is a discrete random variable?

Accepted Answer

The number of cars passing through a toll booth in an hour.

Question 18

Given the confidence interval $$(12.5, 17.3)$$ for a population mean, what is the margin of error $$E$$?

Accepted Answer

$$E = \frac{17.3 - 12.5}{2} = 2.4$$

Question 19

A point at coordinates $$(8, 2) on a $$scatterplot is far from the regression line and has a large effect on the slope. This point is:

Accepted Answer

Both an outlier and an influential point.

Question 20

A researcher wants to test if the mean cholesterol level in a population is different from $$200 mg/dL. $$Express the null and alternative hypotheses in symbolic form.

Accepted Answer

Null: $$H_0$$: \mu = 200$$; Alternative: H_1$: \mu 
eq 200$$

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