AlgebraEasy–MediumMeaning of the constant in a cooling model
Algebra practice question
The temperature, in degrees Celsius, of a cup of coffee t minutes after it is poured is modelled by T(t) = 90 − 2t. What does the number 90 represent in this model?
- A. The temperature of the coffee when it is poured.Correct
- B. The number of minutes until the coffee is cold.
- C. The number of degrees the coffee cools each minute.
- D. The temperature of the room.
Answer: A. The temperature of the coffee when it is poured.
At t = 0 — the moment of pouring — T(0) = 90. The constant is the starting temperature.
Why the other answers are wrong
- B. The number of minutes until the coffee is cold.
- Time isn't measured in degrees; 90 is the value of T, not of t.
- C. The number of degrees the coffee cools each minute.
- The cooling per minute is the 2 in −2t.
- D. The temperature of the room.
- Nothing in the model refers to the room; 90 is the coffee's temperature at t = 0.
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