PSLE
The graph shows the temperature of water in a pot from 2000 to 20 30.
- For how many minutes was the temperature of the water 70°C and below? Give your answer in min.
- During which two 5-minute intervals did the temperature of water decrease at the same rate? Give your answer in the following format. (Eg 01 00 to 01 15, 01 25 to 01 30)
- What was the change in temperature per minute from 2020 to 2025? Give your answer in °C/min.
(a)
Temperature of water that reached 55°C at 20 10.
From 20 05 to 20 30: 25 min
Duration that the temperature of water that reached 70°C and below = 25 min
(b)
Decrease in temperature of water
From 20 00 to 20 05: 78°C - 70°C = 8°C
From 20 5 to 20 10: 70°C - 55°C = 15°C
From 20 10 to 20 15: 55°C - 46°C = 9°C
From 20 15 to 20 20: 46°C - 28°C = 18°C
From 20 20 to 20 25: 28°C - 18°C =
10°C
From 20 25 to 20 30: 18°C - 8°C =
10°C
Two 5-minute intervals that the temperature of water decreas
es at the same rate are 20 15 to 20 20 and 20 20 to 20 25. (c)
Change in temperature per minute from 20 20 to 20 25
= 10 ÷ 5
= 2°C/min
Answer(s): (a) 25 min; (b) 20 15 to 20 20, 20 20 to 20 25; (c) 2°C/min