Q: Suppose the cost of a statistics textbook was $$55 in 1985 and 105 in 2000. $$What is the 'Statistics Text Index' for 2000, using 1985 as the reference value? (Round to the nearest tenth)

$$\frac{105}{55} \times 100 = 190.9$$

Q: You are dealt two cards successively (without replacement) from a shuffled deck of 52 playing cards. What is the probability that both cards are red?

$$\frac{26}{52} \times \frac{25}{51} \approx 0.245$$

Question 1

A marketing firm surveys 100 people and finds that 15 use a product. Is this study experimental or observational?

Accepted Answer

Observational, because the firm only observes and records responses.

Question 2

A clinic gives a drug to one group and a placebo to another to test effects. Is this study experimental or observational?

Accepted Answer

Experimental, because the clinic assigns treatments to groups.

Question 3

A sample of fish is taken from a lake to measure pollution effects. Is this study experimental or observational?

Accepted Answer

Observational, because the researcher only observes existing conditions.

Question 4

The average age of 45 employees in a large company is found to be 32 years. Is this group a population or a sample?

Accepted Answer

Sample, because only a subset of employees is evaluated.

Question 5

A researcher examines records of all registered voters in a city and finds 43% are Democrats. Is this group a population or a sample?

Accepted Answer

Population, because all registered voters in the city are included.

Question 6

A poll of 700 persons at the Taste of Chicago showed 65% believed the food was overpriced. What is the raw data of the study?

Accepted Answer

The individual responses from each of the 700 persons surveyed.

Question 7

A news article claims ethanol releases fewer toxic chemicals than petroleum-based fuels, but the Farmers Association financed the research. What is a possible source of bias?

Accepted Answer

The Farmers Association may have a vested interest in positive results for ethanol.

Question 8

Salaries of college professors are best measured at which level?

Accepted Answer

Ratio

Question 9

Survey responses of 'good', 'better', 'best' are best measured at which level?

Accepted Answer

Ordinal

Question 10

Suppose the cost of a statistics textbook was $$55 in 1985 and 105 in 2000. $$What is the 'Statistics Text Index' for 2000, using 1985 as the reference value? (Round to the nearest tenth)

Accepted Answer

$$\frac{105}{55} 	imes 100 = 190.9$$

Question 11

The amount of credit card debt of families in the U.S. is most likely to have which type of distribution?

Accepted Answer

Right-skewed

Question 12

Shoe sizes of adult women are most likely to have which type of distribution?

Accepted Answer

Symmetric

Question 13

The heights of a large population of students have a mean of 60 inches and a standard deviation of 4 inches. What is the mean of the distribution of sample means for $$n = 16$$?

Accepted Answer

$$60$$

Question 14

A final exam in Math 160 has a mean of 73 and standard deviation 7.73. For a random sample of 24 students, what percentage of sample means are less than 76? (Assume normal distribution, round to two decimal places)

Accepted Answer

Approximately $$97.72\%$$

Question 15

Of 1841 people who came into a blood bank, 218 had high blood pressure. Estimate the probability that the next person will have high blood pressure.

Accepted Answer

$$\frac{218}{1841} \approx 0.118$$

Question 16

You are dealt two cards successively (without replacement) from a shuffled deck of 52 playing cards. What is the probability that both cards are red?

Accepted Answer

$$\frac{26}{52} 	imes \frac{25}{51} \approx 0.245$$

Question 17

In one town, 37% of all voters are Democrats. If two voters are randomly selected, what is the probability that both are Democrats?

Accepted Answer

$$0.37 	imes 0.37 = 0.1369$$

Question 18

Estimate the coordinates of the outlier in the provided scatterplot.

Accepted Answer

(9, 16)

Question 19

How does the outlier at (9, 16) affect the correlation coefficient of the data?

Accepted Answer

It decreases the correlation coefficient.

Estimating Outliers and Their Effect on Correlation

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