PSLE
The graph shows the temperature of water in a pot from 1600 to 16 48.
- For how many minutes was the temperature of the water 55°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 1640 to 1648? Give your answer in °C/min.
(a)
Temperature of water that reached 55°C at 16 16.
From 16 16 to 16 48: 32 min
Duration that the temperature of water that reached 55°C and below = 32 min
(b)
Decrease in temperature of water
From 16 00 to 16 08: 85°C - 71°C = 14°C
From 16 8 to 16 16: 71°C - 55°C = 16°C
From 16 16 to 16 24: 55°C - 40°C = 15°C
From 16 24 to 16 32: 40°C - 30°C =
10°C
From 16 32 to 16 40: 30°C - 11°C = 19°C
From 16 40 to 16 48: 11°C - 1°C =
10°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 16 24 to 16 32 and 16 40 to 16 32. (c)
Change in temperature per minute from 16 40 to 16 48
= 4 ÷ 8
= 0.5°C/min
Answer(s): (a) 32 min; (b) 16 24 to 16 32, 16 24 to 16 32; (c) 0.5°C/min