Problem-Solving and Data AnalysisMediumInterpreting the intercept and slope of a line of best fit
Problem-Solving and Data Analysis practice question
A line of best fit relating the number of hours t a lamp has been on to the fuel y, in millilitres, left in its reservoir is y = 300 − 25t. Which statement is the best interpretation of the model?
- A. The reservoir held about 300 mL when the lamp was lit, and the lamp uses about 25 mL per hour.Correct
- B. The reservoir held about 25 mL when the lamp was lit, and the lamp uses about 300 mL per hour.
- C. The lamp burns for 300 hours.
- D. The lamp uses 25 mL in total.
Answer: A. The reservoir held about 300 mL when the lamp was lit, and the lamp uses about 25 mL per hour.
Intercept 300 is the starting fuel; slope −25 is the hourly use.
Why the other answers are wrong
- B. The reservoir held about 25 mL when the lamp was lit, and the lamp uses about 300 mL per hour.
- Swaps the roles of the numbers.
- C. The lamp burns for 300 hours.
- It burns for 300/25 = 12 hours.
- D. The lamp uses 25 mL in total.
- 25 mL is the rate per hour, not the total.
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