Problem-Solving and Data AnalysisMediumLine of best fit
Problem-Solving and Data Analysis practice question
A scatterplot relates hours studied (x) to test score (y). The line of best fit is y = 3x + 60.
Based on the model, what score does the line predict for a student who studies 5 hours?
- A. 63
- B. 68
- C. 72
- D. 75Correct
Answer: D. 75
Substitute x = 5: y = 3(5) + 60 = 15 + 60 = 75. Read the equation as 'score = 3 points per study-hour, starting from 60'.
Why the other answers are wrong
- A. 63
- You added 3 to 60 instead of multiplying by the 5 hours: y = 3(5) + 60 = 75.
- B. 68
- You added the 5 hours and the slope 3 to 60 (60 + 5 + 3). The slope must be multiplied by the hours: 3 × 5 = 15, so y = 75.
- C. 72
- There's no operation on 3, 5, and 60 that gives 72 — substitute directly: y = 3(5) + 60 = 15 + 60 = 75.
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