Choosing a model and percentage change
Choosing a model and percentage change
Secondary 2
A coach driver records the average speed, \(v\) km/h, and the time taken, \(t\) hours, for the trip from the depot to a school on three days.
| \(v\) | \(40\) | \(50\) | \(80\) |
|---|---|---|---|
| \(t\) | \(3\) | \(2.4\) | \(1.5\) |
- Decide whether \(t\) is directly proportional to \(v\), inversely proportional to \(v\), or neither. Justify your answer and find an equation connecting \(t\) and \(v\).
- Find the time taken at \(60\) km/h.
- The speed is increased by \(25\%\). Find the percentage decrease in the time taken.
Solution:
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Answer:(a) \(t=\dfrac{120}{v}\)
(b) \(2\) hours
(c) \(20\%\) decrease
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