AlgebraMediumMeaning of the slope in a savings model
Algebra practice question
The amount of money in a savings jar is modelled by S(w) = 15 + 8w, where w is the number of weeks since the jar was started. Which of the following is the best interpretation of the number 8?
- A. $8 is added to the jar each week.Correct
- B. The jar started with $8.
- C. The jar will be full after 8 weeks.
- D. The jar held $8 after one week.
Answer: A. $8 is added to the jar each week.
The coefficient of w is the weekly change: $8 per week.
Why the other answers are wrong
- B. The jar started with $8.
- The starting amount is 15.
- C. The jar will be full after 8 weeks.
- Nothing in the model says when the jar is full.
- D. The jar held $8 after one week.
- After one week the jar holds 15 + 8 = 23.
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