ACT Math · Statistics & Probability
Statistics and data analysis practice questions
Each free question on this page comes with its answer and a full explanation.
- Question 30The mean of 6 numbers is 18. If one of the numbers is removed, the mean of the remaining 5 numbers is 20. What was the value of…
- Question 34A distribution has a mean of 70 and a standard deviation of 8. What is the z-score for a value of 82?
- Question 41One class of 20 students has an average test score of 85. A second class of 30 students has an average score of 90. What is the…
- Question 72What is the median of the data set 4, 7, 7, 9, 12, 15, 7, 20?
- Question 75Data set A has a standard deviation of 4. Data set B has a standard deviation of 9. Both sets have the same mean. Which set has…
- Question 76A box plot shows a first quartile of 15 and a third quartile of 35. What is the interquartile range?
- Question 77A scatterplot has a correlation coefficient of r = -0.85. Which best describes the relationship?
- Question 119A student's test score is at the 75th percentile. What does this mean?
- Question 120A researcher wants to know how often adults in a city exercise. She surveys only people leaving a gym. What is the main concern…
- Question 128A student's final grade is based 70% on exams (average 82) and 30% on homework (average 95). What is the student's weighted…
- Question 158What is the range of the data set 2, 5, 6, 8, 9, 11, 45?
- Question 159A frequency table shows the value 1 occurring 5 times, 2 occurring 8 times, 3 occurring 4 times, and 4 occurring 3 times. What…
- Question 161A distribution has mean 100 and standard deviation 15. According to the empirical rule, approximately what percent of values…
- Question 163For the data set 3, 4, 5, 6, 50, how do the mean and median compare?
- Question 202What is the population standard deviation of the data set 4, 8, 6, 10, 12? (Round to the nearest hundredth.)
- Question 205Group A has a median of 60 and an IQR of 10. Group B has a median of 75 and an IQR of 20. Which group shows more variability in…
- Question 206A line of best fit for a data set is y = 2.5x + 10. Using this model, what value of y is predicted when x = 8?
- Question 214One class of 15 students has an average score of 80. A second class of 5 students has an average score of 90. What is the…
- Question 272The data set 10, 12, 14, 16, 90 includes an outlier. By how much does removing the outlier change the mean?
- Question 273A study finds a strong positive correlation between monthly ice cream sales and the number of drowning incidents. What is the…
- Question 275A stem-and-leaf plot has the following rows: stem 2 with leaves 1, 5, 8; stem 3 with leaves 0, 2, 2, 9; stem 4 with leaves 1, 5.…
- Question 277In a survey of 400 people, 250 said they prefer Product A. What is the sample proportion who prefer Product A?
- Question 278What is the range of the data set 5, 7, 9, 11, 50?
- Question 279Team A has an average score of 82 over 10 games. Team B has an average score of 78 over 15 games. By how much does Team A's…
- Question 291A student has test scores of 85, 90, and 78 on the first three tests. What score is needed on the fourth test for the student's…