PSLE
The graph shows the temperature of water in a pot from 1600 to 16 30.
- For how many minutes was the temperature of the water 55°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 1625 to 1630? Give your answer in °C/min.
(a)
Temperature of water that reached 55°C at 16 10.
From 16 10 to 16 30: 20 min
Duration that the temperature of water that reached 55°C and below = 20 min
(b)
Decrease in temperature of water
From 16 00 to 16 05: 86°C - 74°C = 12°C
From 16 5 to 16 10: 74°C - 55°C = 19°C
From 16 10 to 16 15: 55°C - 38°C = 17°C
From 16 15 to 16 20: 38°C - 27°C =
11°C
From 16 20 to 16 25: 27°C - 22°C = 5°C
From 16 25 to 16 30: 22°C - 11°C =
11°C
Two 5-minute intervals that the temperature of water decreas
es at the same rate are 16 15 to 16 20 and 16 25 to 16 20. (c)
Change in temperature per minute from 16 25 to 16 30
= 4 ÷ 5
= 0.8°C/min
Answer(s): (a) 20 min; (b) 16 15 to 16 20, 16 15 to 16 20; (c) 0.8°C/min