CLAST Statistics and Probability 5 — Questions and Answers
Question 1: A scatter plot shows a strong positive correlation between study hours and test scores. Which statement is best supported?
- Test scores cause more study hours
- More study hours are associated with higher test scores (Correct answer)
- Study hours have no effect on test scores
- The relationship is negative
Correct answer: More study hours are associated with higher test scores
A positive correlation means that as study hours increase, test scores tend to increase as well.
Question 2: A class of 30 students took a quiz. The median score was 74. What does this tell us?
- Half the class scored below 74 (Correct answer)
- The average score is 74
- Most students scored 74
- 74 is the highest score
Correct answer: Half the class scored below 74
The median is the middle value, meaning exactly half the scores fall below and half above 74.
Question 3: A card is drawn from a standard 52-card deck. What is the probability it is a face card (Jack, Queen, or King)?
- 1/4
- 3/13 (Correct answer)
- 3/52
- 1/13
Correct answer: 3/13
There are 12 face cards in a deck of 52, so P = 12/52 = 3/13.
Question 4: The interquartile range (IQR) of a data set is 18. Q1 = 22. What is Q3?
- 4
- 36
- 40 (Correct answer)
- 44
Correct answer: 40
IQR = Q3 − Q1, so Q3 = IQR + Q1 = 18 + 22 = 40.
Question 5: Which of the following describes a sample that is likely to produce biased results?
- A random sample of 500 voters from across the state
- Surveying only students who visit the school library (Correct answer)
- Using a computer to randomly select participants
- Drawing names from a hat
Correct answer: Surveying only students who visit the school library
Surveying only library visitors excludes students who never use the library, creating a non-representative sample.
Question 6: A data set's values range from 20 to 80. If you add a new data point of 500, which measure changes the LEAST?
- Mean
- Range
- Median (Correct answer)
- Standard deviation
Correct answer: Median
Adding one extreme outlier has little effect on the median because it only shifts the middle position slightly.
Question 7: A student rolls a six-sided die three times. What is the probability of rolling a 6 on all three rolls?
- 1/6
- 1/18
- 1/36
- 1/216 (Correct answer)
Correct answer: 1/216
Each roll is independent, so P(6 three times) = (1/6)³ = 1/216.
CLAST Statistics and Probability 5
A scatter plot shows a strong positive correlation between study hours and test scores.
Which statement is best supported?