PSLE
The graph shows the temperature of water in a pot from 1200 to 12 30.
- For how many minutes was the temperature of the water 70°C and below? Give your answer in min.
- During which two 5-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 1220 to 1225? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 12 10.
From 12 05 to 12 30: 25 min
Duration that the temperature of water that reached 70°C and below = 25 min
(b)
Decrease in temperature of water
From 12 00 to 12 05: 83°C - 70°C = 13°C
From 12 5 to 12 10: 70°C - 60°C = 10°C
From 12 10 to 12 15: 60°C - 53°C = 7°C
From 12 15 to 12 20: 53°C - 47°C = 6°C
From 12 20 to 12 25: 47°C - 29°C =
18°C
From 12 25 to 12 30: 29°C - 11°C =
18°C
Two 5-minute intervals that the temperature of water decreas
es at the same rate are 12 15 to 12 20 and 12 20 to 12 25. (c)
Change in temperature per minute from 12 20 to 12 25
= 18 ÷ 5
= 3.6°C/min
Answer(s): (a) 25 min; (b) 12 15 to 12 20, 12 20 to 12 25; (c) 3.6°C/min