PTA PTA Data Interpretation and Analysis 2

Question 1

What type of graph is best for showing how a quantity changes over time?

Accepted Answer

Line graph

Answer

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?

Accepted Answer

60%

Answer

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)?

Accepted Answer

Mean

Answer

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?

Accepted Answer

1/2

Answer

Total = 15 + 25 + 10 = 50; Blue fraction = 25/50 = 1/2.

Question 5

What does a negative correlation in a scatter plot indicate?

Accepted Answer

As one variable increases, the other decreases

Answer

A negative correlation means that as one variable increases, the other variable tends to decrease.

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