PTA PTA Data Interpretation and Analysis 2 — Questions and Answers
Question 1: What type of graph is best for showing how a quantity changes over time?
- Pie chart
- Bar chart
- Line graph (Correct answer)
- Scatter plot
Correct answer: Line graph
Line graphs are best suited for showing how a value changes continuously over a period of time.
Question 2: A survey shows 120 people like coffee, 80 like tea, and 40 like juice. What percentage prefer coffee?
- 40%
- 50%
- 60% (Correct answer)
- 70%
Correct answer: 60%
Total = 120 + 80 + 40 = 240; coffee % = (120 ÷ 240) × 100 = 50%... wait: 120/240 = 0.5 = 50%. The correct answer is 50%.
Question 3: In a data set, which measure of central tendency is most affected by extreme values (outliers)?
- Mode
- Median
- Mean (Correct answer)
- Range
Correct answer: Mean
The mean (average) is most affected by outliers because it uses all values in the calculation.
Question 4: A frequency table shows: Red=15, Blue=25, Green=10. What fraction of responses chose Blue?
- 1/4
- 1/2 (Correct answer)
- 1/3
- 5/12
Correct answer: 1/2
Total = 15 + 25 + 10 = 50; Blue fraction = 25/50 = 1/2.
Question 5: What does a negative correlation in a scatter plot indicate?
- As one variable increases, the other also increases
- As one variable increases, the other decreases (Correct answer)
- There is no relationship between variables
- Both variables remain constant
Correct answer: As one variable increases, the other decreases
A negative correlation means that as one variable increases, the other variable tends to decrease.
Question 6: A bar chart shows monthly rainfall. If June had 4 inches and July had 6 inches, by what percent did rainfall increase?
- 25%
- 33%
- 50% (Correct answer)
- 66%
Correct answer: 50%
Percent increase = ((6 − 4) ÷ 4) × 100 = (2 ÷ 4) × 100 = 50%.
PTA PTA Data Interpretation and Analysis 2
What type of graph is best for showing how a quantity changes over time?