PSLE
The graph shows the temperature of water in a pot from 1700 to 17 48.
- For how many minutes was the temperature of the water 80°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 1732 to 1740? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 17 16.
From 17 08 to 17 48: 40 min
Duration that the temperature of water that reached 80°C and below = 40 min
(b)
Decrease in temperature of water
From 17 00 to 17 08: 95°C - 80°C = 15°C
From 17 8 to 17 16: 80°C - 60°C = 20°C
From 17 16 to 17 24: 60°C - 55°C = 5°C
From 17 24 to 17 32: 55°C - 47°C = 8°C
From 17 32 to 17 40: 47°C - 31°C =
16°C
From 17 40 to 17 48: 31°C - 15°C =
16°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 17 24 to 17 32 and 17 32 to 17 40. (c)
Change in temperature per minute from 17 32 to 17 40
= 16 ÷ 8
= 2°C/min
Answer(s): (a) 40 min; (b) 17 24 to 17 32, 17 32 to 17 40; (c) 2°C/min