DSAT Data Analysis 2 — Questions and Answers
Question 1: A scatterplot shows hours studied vs. test scores for 20 students. The line of best fit is y = 5.2x + 48. What does the slope 5.2 represent?
- The minimum score a student can earn
- The predicted score increase for each additional hour studied (Correct answer)
- The average number of hours all students studied
- The y-intercept of the regression line
Correct answer: The predicted score increase for each additional hour studied
The slope represents the predicted change in y for each one-unit increase in x.
Question 2: A dataset has values: 12, 15, 15, 18, 20, 22, 95. Which measure of center best represents the typical value?
- Mean
- Median (Correct answer)
- Mode
- Range
Correct answer: Median
The median is resistant to the outlier 95, making it the best measure of center for skewed data.
Question 3: A survey of 400 people found that 60% prefer brand A, with a margin of error of ±4%. Which interval most likely contains the true population proportion?
- 54% to 60%
- 56% to 64% (Correct answer)
- 60% to 64%
- 58% to 62%
Correct answer: 56% to 64%
Applying ±4% to 60% gives the confidence interval 56% to 64%.
Question 4: Which correlation coefficient best describes a strong negative linear relationship?
- r = 0.92
- r = -0.04
- r = -0.88 (Correct answer)
- r = 0.15
Correct answer: r = -0.88
A value of r = -0.88 indicates a strong negative linear relationship because it is close to -1.
Question 5: A box plot shows: minimum = 10, Q1 = 25, median = 40, Q3 = 55, maximum = 70. What is the interquartile range (IQR)?
- 60
- 30 (Correct answer)
- 40
- 15
Correct answer: 30
IQR = Q3 − Q1 = 55 − 25 = 30.
Question 6: A researcher finds a strong positive correlation between shoe size and reading ability in children ages 5–12. What is the most likely explanation?
- Larger shoe size causes better reading
- Better reading causes larger feet
- Age is a confounding variable driving both (Correct answer)
- The data must contain errors
Correct answer: Age is a confounding variable driving both
Age is a confounding variable; as children grow older, both shoe size and reading ability improve independently.
Question 7: A frequency table shows 30 students scored 70–79, 50 scored 80–89, and 20 scored 90–99. What percentage of students scored 80 or above?
- 50%
- 60%
- 70% (Correct answer)
- 80%
Correct answer: 70%
Students scoring 80+ = 50 + 20 = 70 out of 100 total = 70%.
DSAT Data Analysis 2
A scatterplot shows hours studied vs. test scores for 20 students.
The line of best fit is y = 5.2x + 48.
What does the slope 5.2 represent?