SC READY Data Analysis, Statistics & Probability 2 — Questions and Answers
Question 1: The following data set shows quiz scores: 55, 62, 70, 72, 74, 78, 85, 90. What is the median score?
- 72
- 74
- 73 (Correct answer)
- 70
Correct answer: 73
With 8 values, the median is the average of the 4th and 5th values (72 and 74): (72+74)/2 = 73.
Question 2: A stem-and-leaf plot shows the following data — Stem 3: leaves 1, 5, 8; Stem 4: leaves 0, 2, 7. What is the greatest value in the data set?
- 40
- 47 (Correct answer)
- 38
- 42
Correct answer: 47
The stem 4 with leaf 7 represents the value 47, which is the largest value in the plot.
Question 3: A survey asked 50 students how they travel to school. 20 walk, 15 ride the bus, 10 are driven by car, and 5 ride bikes. Which display would BEST show the percentage each travel method represents?
- Bar graph
- Line graph
- Pie chart (Correct answer)
- Stem-and-leaf plot
Correct answer: Pie chart
A pie chart is best for showing parts of a whole as percentages, making it ideal for comparing proportions of categories.
Question 4: If you flip a fair coin three times, what is the probability of getting heads all three times?
- 1/2
- 1/4
- 1/6
- 1/8 (Correct answer)
Correct answer: 1/8
Each flip has a 1/2 probability; for three independent flips, multiply: 1/2 × 1/2 × 1/2 = 1/8.
Question 5: A box-and-whisker plot for a data set shows: minimum = 10, Q1 = 20, median = 35, Q3 = 50, maximum = 70. What is the interquartile range (IQR)?
- 60
- 30 (Correct answer)
- 25
- 15
Correct answer: 30
The IQR = Q3 − Q1 = 50 − 20 = 30, representing the spread of the middle 50% of the data.
Question 6: A student recorded the number of minutes spent on homework each night: 30, 45, 60, 30, 90, 30, 45. After adding one more day with 90 minutes, what happens to the mode?
- The mode changes to 45
- The mode changes to 90
- There are now two modes: 30 and 90 (Correct answer)
- The mode stays 30
Correct answer: There are now two modes: 30 and 90
After adding 90, both 30 and 90 appear three times each, making the data set bimodal with two modes.
Question 7: A frequency table shows that 10 students scored 70–79, 15 scored 80–89, and 5 scored 90–99. How many students scored below 90?
- 15
- 10
- 25 (Correct answer)
- 30
Correct answer: 25
Students scoring below 90 are those in the 70–79 range (10) and 80–89 range (15), totaling 25 students.
SC READY Data Analysis, Statistics & Probability 2
The following data set shows quiz scores: 55, 62, 70, 72, 74, 78, 85, 90.
What is the median score?