PSLE
The graph shows the temperature of water in a pot from 1300 to 13 30.
- For how many minutes was the temperature of the water 50°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 1325 to 1330? Give your answer in °C/min.
(a)
Temperature of water that reached 50°C at 13 10.
From 13 10 to 13 30: 20 min
Duration that the temperature of water that reached 50°C and below = 20 min
(b)
Decrease in temperature of water
From 13 00 to 13 05: 87°C - 70°C = 17°C
From 13 5 to 13 10: 70°C - 50°C = 20°C
From 13 10 to 13 15: 50°C - 42°C = 8°C
From 13 15 to 13 20: 42°C - 35°C =
7°C
From 13 20 to 13 25: 35°C - 26°C = 9°C
From 13 25 to 13 30: 26°C - 19°C =
7°C
Two 5-minute intervals that the temperature of water decreas
es at the same rate are 13 15 to 13 20 and 13 25 to 13 20. (c)
Change in temperature per minute from 13 25 to 13 30
= 1 ÷ 5
= 0.2°C/min
Answer(s): (a) 20 min; (b) 13 15 to 13 20, 13 15 to 13 20; (c) 0.2°C/min