PSLE
The graph shows the temperature of water in a pot from 1700 to 17 36.
- For how many minutes was the temperature of the water 70°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 1724 to 1730? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 17 12.
From 17 06 to 17 36: 30 min
Duration that the temperature of water that reached 70°C and below = 30 min
(b)
Decrease in temperature of water
From 17 00 to 17 06: 83°C - 70°C = 13°C
From 17 6 to 17 12: 70°C - 60°C = 10°C
From 17 12 to 17 18: 60°C - 51°C = 9°C
From 17 18 to 17 24: 51°C - 40°C = 11°C
From 17 24 to 17 30: 40°C - 25°C =
15°C
From 17 30 to 17 36: 25°C - 10°C =
15°C
Two 6-minute intervals that the temperature of water decreas
es at the same rate are 17 18 to 17 24 and 17 24 to 17 30. (c)
Change in temperature per minute from 17 24 to 17 30
= 15 ÷ 6
= 2.5°C/min
Answer(s): (a) 30 min; (b) 17 18 to 17 24, 17 24 to 17 30; (c) 2.5°C/min