PSLE
The graph shows the temperature of water in a pot from 1200 to 12 48.
- For how many minutes was the temperature of the water 60°C and below? Give your answer in min.
- During which two 8-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 1232 to 1240? Give your answer in °C/min.
(a)
Temperature of water that reached 45°C at 12 16.
From 12 08 to 12 48: 40 min
Duration that the temperature of water that reached 60°C and below = 40 min
(b)
Decrease in temperature of water
From 12 00 to 12 08: 78°C - 60°C = 18°C
From 12 8 to 12 16: 60°C - 45°C = 15°C
From 12 16 to 12 24: 45°C - 31°C = 14°C
From 12 24 to 12 32: 31°C - 14°C = 17°C
From 12 32 to 12 40: 14°C - 8°C =
6°C
From 12 40 to 12 48: 8°C - 2°C =
6°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 12 24 to 12 32 and 12 32 to 12 40. (c)
Change in temperature per minute from 12 32 to 12 40
= 6 ÷ 8
= 0.75°C/min
Answer(s): (a) 40 min; (b) 12 24 to 12 32, 12 32 to 12 40; (c) 0.75°C/min