PSLE
The graph shows the temperature of water in a pot from 1200 to 12 36.
- For how many minutes was the temperature of the water 60°C and below? Give your answer in min.
- During which two 6-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 1230 to 1236? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 12 12.
From 12 12 to 12 36: 24 min
Duration that the temperature of water that reached 60°C and below = 24 min
(b)
Decrease in temperature of water
From 12 00 to 12 06: 81°C - 67°C = 14°C
From 12 6 to 12 12: 67°C - 60°C = 7°C
From 12 12 to 12 18: 60°C - 41°C = 19°C
From 12 18 to 12 24: 41°C - 28°C =
13°C
From 12 24 to 12 30: 28°C - 22°C = 6°C
From 12 30 to 12 36: 22°C - 9°C =
13°C
Two 6-minute intervals that the temperature of water decreas
es at the same rate are 12 18 to 12 24 and 12 30 to 12 24. (c)
Change in temperature per minute from 12 30 to 12 36
= 6 ÷ 6
= 1°C/min
Answer(s): (a) 24 min; (b) 12 18 to 12 24, 12 18 to 12 24; (c) 1°C/min