Question 1

A college has the following dorm residents by class: Freshmen: 128, Sophomore: 112, Junior: 96, Senior: 48. If a researcher wants to draw a stratified random sample of 100 residents, how many should be selected from the Junior class?

Accepted Answer

24

Question 2

A researcher polls 1000 people from California and Florida about the 2024 presidential election. The results are: Trump 43%, Harris 50%, Others 7%. The researcher concludes Trump will be less likely to win the presidency. Which is the best critique of this conclusion?

Accepted Answer

The sample is not representative of the entire U.S. population.

Question 3

In the IPO data table, what type of data is presented in the 1st column (Rank), 2nd column (Company), and 3rd column (IPO value)?

Accepted Answer

1st: Ordinal, 2nd: Nominal, 3rd: Ratio

Question 4

A histogram shows cholesterol levels for patients. If the relative frequency for the interval 215–225 mg/dL is 0.15, what percentage of patients have cholesterol levels of 215 or higher?

Accepted Answer

15%

Question 5

Given the following wealth values (in billions): 66, 46, 42, 31, 31, 27.9, 26.8, 26.3, 26.1, 25. What is the mean wealth?

Accepted Answer

$$\frac{66+46+42+31+31+27.9+26.8+26.3+26.1+25}{10} = 34.21$$

Question 6

A sample of 5 U.S. residents have ages: 21, 54, 9, 45, 51. What is the range of these ages?

Accepted Answer

$$54 - 9 = 45$$

Question 7

A sample of 5 U.S. residents have ages: 21, 54, 9, 45, 51. What is the sample mean?

Accepted Answer

$$\frac{21+54+9+45+51}{5} = 36$$

Question 8

A sample of 5 U.S. residents have ages: 21, 54, 9, 45, 51. What is the sample standard deviation?

Accepted Answer

$$\sqrt{\frac{(21-36)^2$+(54-36)^2+(9-36)^2$+(45-36)^2+(51-36)^2$}{4}} = 19.52$$

Question 9

The first histogram image shows a distribution. What type of skewness does it display?

Accepted Answer

It is symmetric (no skewness).

Question 10

The second histogram image shows a biomarker distribution. What type of skewness does it display?

Accepted Answer

It is positively skewed (right-skewed).

Question 11

For a positively skewed distribution, how does the mean compare to the median?

Accepted Answer

The mean is greater than the median.

Question 12

A sample of 225 Swedish men has a mean brain weight of 1.40 kg and standard deviation of 0.11 kg. According to the Empirical Rule, what percentage of observations fall within 2 standard deviations of the mean?

Accepted Answer

Approximately 95%

Question 13

A sample of 225 Swedish men has a mean brain weight of 1.40 kg and standard deviation of 0.11 kg. What is the interval for 1 standard deviation from the mean?

Accepted Answer

$$1.40 \pm 0.11 = [1.29, 1.51]$$

Question 14

In a study of memory recall times, the box plot for unpleasant memories shows a higher median and greater variation than pleasant memories. What does this suggest?

Accepted Answer

Unpleasant memory recall times tend to be longer and more variable.

Question 15

Which of the following is an example of ratio data?

Accepted Answer

Cholesterol level measured in mg/dL

Question 16

If a histogram is symmetric, which measure of central tendency is most appropriate?

Accepted Answer

Mean

Question 17

If a researcher wants to compare the variation between two groups, which statistic is most appropriate?

Accepted Answer

Standard deviation

Question 18

Which of the following best describes the mode in a dataset?

Accepted Answer

The value that appears most frequently

Step-by-Step Guidance for Statistics Quiz #1 (Chapters 1–3)

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드