GRE General TestQuantitative ReasoningEasy
A technician is monitoring the temperature of an experimental substance. The temperature is currently 25°C and is decreasing at a constant rate of 3°C per hour. What will be the temperature of the substance after 4 hours?
- A22°C
- B16°C
- C13°C
- D10°C
Show answer & explanationAnswer & explanation
Correct answer: C. 13°C
To find the temperature after 4 hours, multiply the rate of decrease by the number of hours and subtract this total decrease from the initial temperature.
Why the other options are wrong
- A. This would be the temperature if the decrease was 0.75°C per hour.
- B. This would be the temperature if the decrease was 2.25°C per hour.
- D. This would be the temperature if the decrease was 3.75°C per hour.
Linear Decrease
Linear decrease describes a quantity that reduces by a fixed amount over equal intervals of time or another variable.
- Involves a constant rate of reduction.
- Can be modeled by a linear equation: Final = Initial - (Rate × Time).
- Distinguished from exponential decay where the reduction is proportional to the current amount.
Memory trick: Constant Change: Think of a steady drip reducing a bucket's water level.