Final answer:
By subtracting or adding 3 °C for each hour to the current temperature, we find the future temperatures will be -6 °C in 2 hours, -15 °C in 5 hours, and -1.5 °C in half an hour; past temperatures were 3 °C 1 hour ago and 9 °C 3 hours ago.
Step-by-step explanation:
If the temperature at the top of a mountain is currently 0 °C and decreasing at a rate of 3 °C per hour, we can calculate the future and past temperatures using simple arithmetic. For each hour, we simply subtract 3 °C from or add 3 °C to the current temperature, depending on whether we're calculating the future or past temperature.
- (a) In 2 hours, the temperature will be 0 °C - (2 hours × 3 °C/hour) = 0 °C - 6 °C = -6 °C.
- (b) In 5 hours, the temperature will be 0 °C - (5 hours × 3 °C/hour) = 0 °C - 15 °C = -15 °C.
- (c) In half an hour, the temperature will be 0 °C - (0.5 hours × 3 °C/hour) = 0 °C - 1.5 °C = -1.5 °C.
- (d) 1 hour ago, the temperature was 0 °C + (1 hour × 3 °C/hour) = 0 °C + 3 °C = 3 °C.
- (e) 3 hours ago, the temperature was 0 °C + (3 hours × 3 °C/hour) = 0 °C + 9 °C = 9 °C.