Question 1

A pharmaceutical company wants to test the effectiveness of a new drug. They randomly assign 100 patients to receive the drug and 100 patients to receive a placebo, then compare the outcomes. Which of the following best describes this type of study?

Accepted Answer

Experiment

Question 2

A researcher collects data on the number of hours students study per week and their final exam scores. Which variable is discrete and which is continuous?

Accepted Answer

Hours studied is continuous; exam score is continuous

Question 3

Which of the following is an example of a parameter?

Accepted Answer

The average height of all students in a university

Question 4

A hospital reviews patient records from the past 10 years to study the long-term effects of a treatment. What type of observational study is this?

Accepted Answer

Retrospective

Question 5

Which sampling method is used when a researcher selects every 10th person from a list of patients?

Accepted Answer

Systematic sampling

Question 6

Which level of measurement is represented by the following data: blood types (A, B, AB, O)?

Accepted Answer

Nominal

Question 7

Given the following frequency distribution for test scores: 60-69 (5 students), 70-79 (12 students), 80-89 (8 students), 90-99 (5 students). What is the relative frequency of the 80-89 class?

Accepted Answer

$$ \frac{8}{30} $$

Question 8

A data set has the following values: 2, 4, 4, 6, 8. What is the variance of this data set?

Accepted Answer

$$ 5.0 $$

Question 9

A student receives grades of 80, 85, and 90 in three courses worth 3, 4, and 2 credits, respectively. What is the student's weighted mean grade?

Accepted Answer

$$ 84.44 $$

Question 10

If a value in a data set is at the 75th percentile, what does this mean?

Accepted Answer

75% of the data values are less than or equal to this value

Question 11

Given a data set with a mean of 50 and a standard deviation of 5, what is the z-score for a value of 60?

Accepted Answer

$$ z = 2 $$

Question 12

A histogram is best used for which type of data?

Accepted Answer

Continuous data

Question 13

If a data set has a mean of 100 and a standard deviation of 10, what percentage of data falls within two standard deviations of the mean according to the Empirical Rule?

Accepted Answer

95%

Question 14

Which of the following is NOT a characteristic of a boxplot?

Accepted Answer

Displays the mean

Question 15

A researcher wants to estimate the percentage of data within 3 standard deviations of the mean for any data set, regardless of shape. Which theorem should they use?

Accepted Answer

Chebyshev's Theorem

Question 16

Which of the following is an example of an outlier in a data set of exam scores: 70, 72, 75, 78, 80, 82, 150?

Accepted Answer

150

Question 17

A teacher wants to compare the performance of two students from different classes. Student A scored 85 with a class mean of 80 and standard deviation of 5. Student B scored 78 with a class mean of 70 and standard deviation of 4. Who performed better relative to their class?

Accepted Answer

Student B, because their z-score is higher

Question 18

Which of the following best describes a cross-sectional study?

Accepted Answer

Collects data at a single point in time

Question 19

A researcher divides a population into subgroups based on age and then randomly selects individuals from each subgroup. What type of sampling is this?

Accepted Answer

Stratified sampling

Question 20

If 20% of students scored below 60 on a test, what is the percentile rank of a score of 60?

Accepted Answer

20th percentile

Statistics Study Guide: Chapters 1, 2 & 3

Guida di studio - Domande di pratica

Study guide - Flashcard